Golden State Warriors star Stephen Curry could face an extended period on the sidelines after suffering a sprained knee on Sunday.
After missing two games through an ankle injury, Curry slipped and fell to the floor at the end of the first half in the Warriors' 121-94 win over the Houston Rockets in game four of their NBA play-off series.
Curry warmed up for the second half but went back to the locker room, sitting out the rest of the game.
Coach Steve Kerr said Curry will undergo an MRI on Monday to reveal the full extent of the injury.
"He came out and was sitting on the bench with about three minutes to go," Kerr said.
"He was kind of gathering his thoughts, and we had talked with the doctors about just seeing how he felt, trying it out with a little warm-up session.
"He went out there, tried to move on it. It wasn't right. He still wanted to play. We wouldn't let him. You saw, he was very upset. I feel awful for him.
"But we've got to move on."
Warriors lead 3-1 against the Rockets and can seal the round one series with a win in game five on Wednesday.