DALLAS, TX – DECEMBER 30: Dirk Nowitzki #41 of the Dallas Mavericks lays the ball up against Tim Duncan #21 and Boris Diaw #33 of the San Antonio Spurs on December 30, 2012 at the American Airlines Center in Dallas, Texas. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, User is consenting to the terms and conditions of the Getty Images License Agreement. Mandatory Copyright Notice: Copyright 2012 NBAE (Photo by Glenn James/NBAE via Getty Images)