The Associated Press

DALLAS - Dirk Nowitzki has trouble describing exactly how his sprained left knee feels. He just knows it doesn't feel the way it should.

So, even though the Dallas Mavericks' leading scorer and rebounder says it will be a game-time decision whether he plays tonight against the San Antonio Spurs, he added it would take a drastic improvement for him to be on the court for Game 5 of the Western Conference finals.

"I don't really have pain. It doesn't really hurt. But I can feel that something is not right with my knee," Nowitzki said Monday. "If I have that again tomorrow, I'm not going to play.

"To me, it's got to feel right. If I have any doubts that I can't push off, or have thoughts that I can't get out of my head, then I'm not going to play."

Mavs coach Don Nelson was hoping Nowitzki would at least be able to play 3-on-3 Monday. He couldn't, partly because he pushed himself too hard Sunday.

Nowitzki worked out before Game 4 in hopes of making it into the lineup just two days after being injured. But he wasn't able to run or jump, so he watched San Antonio's 102-95 victory from a seat near the Dallas bench.

The Mavs didn't immediately miss the 25.3 points and 11.5 rebounds Nowitzki has averaged this postseason. For the first 2 1/2 quarters, Dallas' small lineup built a nine-point lead. Then San Antonio rallied and led the entire fourth quarter.

When Dallas began to rally in the final period, Nowitzki stood and cheered until he felt the knee "getting weak and starting to shake."