UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 1 )*
                                             ---
                          Pinnacle Entertainment, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    723456109
                  ---------------------------------------------
                                 (CUSIP Number)

                                December 31, 2003
         --------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

                              [x]  Rule 13d-1(b)
                              [_]  Rule 13d-1(c)
                              [_]  Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

                               Page 1 of 10 pages



----------------------------                        ----------------------------
CUSIP No. 723456109                   13G            Page 2 of 10 Pages
         -------------------
----------------------------                        ----------------------------

--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Columbia Wanger Asset Management, L.P.  36-3820584
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

           Not Applicable                                                (a) [_]
                                                                         (b) [_]
--------------------------------------------------------------------------------
  3     SEC USE ONLY

--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                              None
      SHARES        ------------------------------------------------------------
    BENEFICIALLY       6    SHARED VOTING POWER

      OWNED BY                2,049,000
        EACH        ------------------------------------------------------------
     REPORTING         7    SOLE DISPOSITIVE POWER

      PERSON                  None
       WITH         ------------------------------------------------------------
                       8    SHARED DISPOSITIVE POWER

                              2,049,000
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           2,049,000
--------------------------------------------------------------------------------
  10    CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable
--------------------------------------------------------------------------------
  11    PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           7.9%
--------------------------------------------------------------------------------
  12    TYPE OF REPORTING PERSON*

           IA
--------------------------------------------------------------------------------



----------------------------                        ----------------------------
CUSIP No. 723456109                   13G            Page 3 of 10 Pages
         -------------------
----------------------------                        ----------------------------

--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           WAM Acquisition GP, Inc.
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

           Not Applicable                                                (a) [_]
                                                                         (b) [_]
--------------------------------------------------------------------------------
  3     SEC USE ONLY

--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                              None
      SHARES        ------------------------------------------------------------
    BENEFICIALLY       6    SHARED VOTING POWER

      OWNED BY                2,049,000
        EACH        ------------------------------------------------------------
     REPORTING         7    SOLE DISPOSITIVE POWER

      PERSON                  None
       WITH         ------------------------------------------------------------
                       8    SHARED DISPOSITIVE POWER

                              2,049,000
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           2,049,000
--------------------------------------------------------------------------------
  10    CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable
--------------------------------------------------------------------------------
  11    PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           7.9%
--------------------------------------------------------------------------------
  12    TYPE OF REPORTING PERSON*

           CO
--------------------------------------------------------------------------------



----------------------------                        ----------------------------
CUSIP No. 723456109                   13G            Page 4 of 10 Pages
         -------------------
----------------------------                        ----------------------------

--------------------------------------------------------------------------------
  1     NAME OF REPORTING PERSON
        S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Columbia Acorn Trust
--------------------------------------------------------------------------------
  2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

           Not Applicable                                                (a) [_]
                                                                         (b) [_]
--------------------------------------------------------------------------------
  3     SEC USE ONLY

--------------------------------------------------------------------------------
  4     CITIZENSHIP OR PLACE OF ORGANIZATION

           Massachusetts
--------------------------------------------------------------------------------
                       5    SOLE VOTING POWER
     NUMBER OF
                              None
      SHARES        ------------------------------------------------------------
    BENEFICIALLY       6    SHARED VOTING POWER

      OWNED BY                1,925,000
        EACH        ------------------------------------------------------------
     REPORTING         7    SOLE DISPOSITIVE POWER

      PERSON                  None
       WITH         ------------------------------------------------------------
                       8    SHARED DISPOSITIVE POWER

                              1,925,000
--------------------------------------------------------------------------------
  9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           1,925,000
--------------------------------------------------------------------------------
  10    CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

           Not Applicable
--------------------------------------------------------------------------------
  11    PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

           7.4%
--------------------------------------------------------------------------------
  12    TYPE OF REPORTING PERSON*

           IV
--------------------------------------------------------------------------------



Item 1(a)    Name of Issuer:

                  Pinnacle Entertainment, Inc.

Item 1(b)    Address of Issuer's Principal Executive Offices:

                  3800 Howard Hughes Parkway, Suite 1800
                  Las Vegas, Nevada  89109

Item 2(a)    Name of Person Filing:

                  Columbia Wanger Asset Management, L.P. ("WAM")
                  WAM Acquisition GP, Inc., the general partner of WAM
                  ("WAM GP")
                  Columbia Acorn Trust ("Acorn")

Item 2(b)    Address of Principal Business Office:

                  WAM, WAM GP and Acorn are all located at:

                  227 West Monroe Street, Suite 3000
                  Chicago, Illinois  60606

Item 2(c)    Citizenship:

                  WAM is a Delaware limited partnership; WAM GP is a Delaware
                  corporation; and Acorn is a Massachusetts business trust.

Item 2(d)    Title of Class of Securities:

                  Common Stock

Item 2(e)    CUSIP Number:

                  723456109

Item 3       Type of Person:

                  (d) Acorn is an Investment Company under section 8 of the
                      Investment Company Act.

                  (e) WAM is an Investment Adviser registered under section 203
                      of the Investment Advisers Act of 1940; WAM GP is the
                      General Partner of the Investment Adviser.

                               Page 5 of 10 pages



Item 4        Ownership (at December 31, 2003):

                    (a)  Amount owned "beneficially" within the meaning of rule
                         13d-3:

                         2,049,000

                    (b)  Percent of class:

                         7.9% (based on 25,934,261 shares outstanding as of
                         November 11, 2003).

                    (c)  Number of shares as to which such person
                         has:

                            (i) sole power to vote or to direct the vote: none

                           (ii) shared power to vote or to direct the
                                vote: 2,049,000

                          (iii) sole power to dispose or to direct the
                                disposition of: none

                           (iv) shared power to dispose or to direct disposition
                                of: 2,049,000

Item 5        Ownership of Five Percent or Less of a Class:

                    Not Applicable

Item 6        Ownership of More than Five Percent on Behalf of Another Person:

                    The shares reported herein have been acquired on behalf of
                    discretionary clients of WAM, including Acorn. Persons other
                    than WAM and WAM GP are entitled to receive all dividends
                    from, and proceeds from the sale of, those shares. Acorn is
                    the only such person known to be entitled to all dividends
                    from, and all proceeds from the sale of, shares reported
                    herein to the extent of more than 5% of the class.

Item 7        Identification and Classification of the Subsidiary Which Acquired
              the Security Being Reported on by the Parent Holding Company:

                    Not Applicable

Item 8        Identification and Classification of Members of the Group:

                    Not Applicable

Item 9        Notice of Dissolution of Group:

                    Not Applicable

                               Page 6 of 10 pages



Item 10       Certification:

                   By signing below I certify that, to the best of my knowledge
              and belief, the securities referred to above were acquired and are
              held in the ordinary course of business and were not acquired and
              are not held for the purpose of or with the effect of changing or
              influencing the control of the issuer of the securities and were
              not acquired and are not held in connection with or as a
              participant in any transaction having that purpose or effect.

                               Page 7 of 10 Pages



                                    Signature

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Date: February 13, 2004

                    The undersigned corporation, on the date above written,
                    agrees and consents to the joint filing on its behalf of
                    this Schedule 13G in connection with its beneficial
                    ownership of the security reported herein.

                                     WAM Acquisition GP, Inc.
                                      for itself and as general partner of
                                      COLUMBIA WANGER ASSET
                                      MANAGEMENT, L.P.

                                     By: /s/ Bruce H. Lauer
                                         ---------------------------------------
                                             Bruce H. Lauer
                                             Senior Vice President and Secretary

                    The undersigned trust, on the date above written, agrees and
                    consents to the joint filing on its behalf of this Schedule
                    13G in connection with its beneficial ownership of the
                    security reported herein.

                                     COLUMBIA ACORN TRUST

                                     By: /s/ Bruce H. Lauer
                                         ---------------------------------------
                                             Bruce H. Lauer
                                             Vice President, Treasurer and
                                             Secretary

                               Page 8 of 10 Pages



                                  Exhibit Index

Exhibit 1           Joint Filing Agreement dated as of February 13, 2004 by and
                    among Columbia Wanger Asset Management, L.P., WAM
                    Acquisition GP, Inc. and Columbia Acorn Trust.

                               Page 9 of 10 Pages



                                                                       EXHIBIT 1

                             JOINT FILING AGREEMENT

     The undersigned hereby agree to the joint filing of the Schedule 13G to
which this Agreement is attached.

               Dated: February 13, 2004

                                     WAM Acquisition GP, Inc.
                                      for itself and as general partner of
                                      COLUMBIA WANGER ASSET
                                      MANAGEMENT, L.P.

                                     By: /s/ Bruce H. Lauer
                                         ---------------------------------------
                                             Bruce H. Lauer
                                             Senior Vice President and Secretary

                                     COLUMBIA ACORN TRUST

                                     By: /s/ Bruce H. Lauer
                                         ---------------------------------------
                                             Bruce H. Lauer
                                             Vice President, Treasurer and
                                             Secretary

                              Page 10 of 10 pages