MIAMI - Shaquille O'Neal will undergo knee surgery and be sidelined for four to six weeks, the Miami Heat said Friday. O'Neal tore cartilage in his left knee Sunday when he collided with Houston's Chuck Hayes. The injury was originally diagnosed as a hyperextended knee.

The Heat center sat out Tuesday's game, practiced Thursday and was expected to play Friday against the New York Knicks. But he was listed as inactive, and the Heat announced shortly before tipoff that he would undergo surgery, with the date not disclosed.

O'Neal missed two games earlier in the season with a bruise to the knee.

The defending NBA champions have yet to put their entire starting lineup on the court together. Guard Jason Williams, returning from arthroscopic knee surgery July 21, was active for the first time this season Friday.