Jimmy Butler might be sidelined indefinitely due to a significant knee injury.

The Miami Heat star is feared to have sustained an MCL injury in his team's loss to the Philadelphia 76ers on Wednesday in the play-in tournament, according to The Athletic’s Shams Charania.

Butler is set to undergo an MRI on Thursday to determine the severity of his injury. While specifics are not yet known, it could very easily sideline him indefinitely, which would knock him out of Friday’s win-or-go-home matchup against the Chicago Bulls and potentially much more of the playoffs.

Butler went down hard in the first quarter of the 105-104 loss while going up for a layup, and he was down on the court in obvious pain.

He didn’t exit the game after his fall, however, and ended up playing 40 minutes and dropping 19 points in the loss. Heat coach Erik Spoelstra said Butler’s knee “started to limit him a little more” as the game went on.

“It had me feeling that I couldn’t do too much,” Butler said, via the South Florida Sun-Sentinel’s Ira Winderman.

Butler was limping quite a bit as he walked off the court at the Wells Fargo Center, and his limp seemed significantly worse when he left the arena altogether.

Butler averaged 20.8 points, 5.3 rebounds and five assists per game this season, his fifth with the Heat. He shot just 5-of-18 from the field Wednesday. Tyler Herro led the Heat with 25 points and nine assists in the loss, and Jaime Jaquez Jr. added 15 points off the bench.

Joel Embiid led the 76ers with 23 points and 15 rebounds in their win. Nicolas Batum added 20 points, including six 3-pointers, off the bench. The 76ers clinched the No. 7 seed in the Eastern Conference playoffs, which sets them up with a first-round series against the New York Knicks.

Although Butler has not yet been ruled out, he doesn't have much time to recover before Miami’s next game. The Heat will host the Bulls — who beat the Atlanta Hawks in their play-in tournament matchup Wednesday — on Friday at the Kesaya Center in a must-win game to claim the final seed in the Eastern Conference playoffs. A win would send them into a first-round series with the Boston Celtics.