Russell Westbrook will undergo surgery on his right knee for a lateral meniscus tear.
No timetable for his return has been announced, but it is considered a minimal tear.
Westbrook suffered the injury in the second quarter of Game 2.
Westbrook had never missed a game in his NBA career.
"Maybe," said one source to Yahoo's Adrian Wojnarowski when asked if Westbrook could return in the playoffs.
Westbrook is "irate," with Beverley, a league source told Wojnarowski.
The Thunder and Westbrook don't want to risk any long-term issues with his knee.