The Kansas City Chiefs defeated the Cincinnati Bengals on Sunday to move to 2-0, but lost a key member of the team: star player Isiah Pacheco.

According to NFL Network’s Ian Rapoport, Pacheco fractured his right fibula in the closing stages of the Chiefs’ 26-25 win and will “miss some real games.” ESPN’s Adam Schefter reported that Pacheco has been placed on the injured list, meaning he will miss at least four weeks before he can return.

The fibula is the long, thin bone in your calf that runs from your ankle to your tibia. More tests are reportedly being conducted Monday to assess the severity of Pacheco’s injury and how long he will be out. He could miss just a few weeks, or it could be months before Pacheco is back on the field.

Head coach Andy Reid didn’t have much to say about the injury when he spoke to the media after the game. He hadn’t yet spoken to Pacheco, who was still undergoing tests. When Pacheco left the stadium, he was seen wearing a running boot and crutches.