United States midfielder Tyler Adams has suspected medial collateral ligament damage after limping out of Bournemouth's 4-4 draw with Manchester United in the Premier League on Monday.
In the second minute of the match at Old Trafford, Adams was injured while challenging Matheus Cunha. He came off after treatment on the pitch.
"He's the worst news from the game, definitely," Bournemouth coach Andoni Iraola said. "The knee twisted, I think the MCL. We'll have to check and see if it is a small sprain or bigger.
"To lose a player like Tyler for us is massive, especially when you don't have Lewis Cook (suspended).