LONDON (AP) — Christian Pulisic is facing up to two months out with a knee injury, Chelsea manager Graham Potter said Wednesday.

The United States forward sustained damage to his right knee in Chelsea’s 1-0 loss to Manchester City last week.

“Christian’s going to be out for a couple of months, we think. Hopefully it will be less, but that’s the timeframe there,” Potter said ahead Thursday’s Premier League game against Fulham.

It is the latest injury setback for Pulisic, whose Chelsea career has been disrupted by issues with his fitness.

The 24-year-old former Borussia Dortmund player had started all three of Chelsea’s games since returning from the World Cup in Qatar, but was forced off after 22 minutes against City.

The United States has friendlies against Serbia on January 26 and Colombia on Jan. 29.

Pulisic’s injury is the latest blow for Chelsea, with Reece James, Raheem Sterling, N’Golo Kante, Wesley Fofana and Ben Chilwell among the list of players on the sidelines.

Potter will have Pierre Emerick Aubameyang available after a back problem kept the striker out of Sunday’s 4-0 loss to City in the FA Cup.

Chelsea has also been boosted by the signing of Atletico Madrid forward Joao Felix on loan until the end of the season.

“He is a quality player, and he will make a difference in the final third of the pitch,” Potter said. “He is young, but has really good experience. The signing gives everybody a lift.

“He is a good age and he can play as a second striker between the lines and making a difference in the final third. We are looking forward to working with him.”