Sources: David Lee diagnosed with partially torn patellar tendon

SAN ANTONIO -- Spurs center David Lee has been diagnosed with a partially torn patellar tendon in his left knee and will have an MRI on Sunday to confirm the injury, sources told ESPN.

Lee suffered the injury in the opening quarter of San Antonio's 120-108 loss to the Golden State Warriors on Saturday night and did not return.

Asked about Lee's status after Game 3 of the Western Conference finals, Spurs coach Gregg Popovich said: "I have no idea."

Lee injured the knee with 2:57 remaining in the first quarter after he scored on a layup contested by Draymond Green.

Lee was fouled on the play, but he wasn't able to take the ensuing free throw attempt because of the injury.

Lee winced in pain immediately upon landing, and he was down on the floor near the tunnel leading out toward the locker rooms. Athletic trainers helped Lee to his feet. He hobbled toward the locker room before trainers took over and rushed him down the hall in a wheelchair.

Joel Anthony replaced Lee in the game.

The Spurs later said Lee would not return to the game. By rule, because he was unable to attempt the free throw, he would not have been allowed to return even if he were healthy.

Lee is the club's third player to suffer an injury significant enough to take him out of action. San Antonio already was without star forward Kawhi Leonard, whom Popovich held out because of a sprained left ankle. That injury occurred after the club already had lost Tony Parker in the Western Conference semifinals because of a ruptured quadriceps tendon.

The Warriors lead the West finals 3-0.