Toronto Raptors point guard Kyle Lowry had to be helped off the court after suffering an ankle sprain against Oklahoma City on Tuesday.
Lowry twisted his right ankle after landing on Thunder forward-centre Serge Ibaka's foot while going for a rebound in the second quarter.
Lowry grimaced as he pounded the floor and had to keep his weight off the foot as he went to the locker-room.
He did not return for the second half, and Toronto went on to lose 108-88.
A Raptors team spokesman said Lowry was wearing a walking boot as a precaution, and that he would receive further treatment Wednesday. There is no timetable for his return.
The 26-year-old is playing in his first season with the Raptors after being acquired in the off-season from the Houston Rockets.
Lowry entered Toronto's fourth game of the season averaging 23.7 points per game, 7.3 rebounds per game and seven assists per game.