Manchester United manager Ole Gunnar Solskjaer said both Edinson Cavani and Anthony Martial were substituted during Saturday's 3-1 win over West Ham United because of muscle injuries.
Uruguayan striker Cavani, who scored twice as a substitute against Southampton last weekend, was operating as the central striker against West Ham, but did not come out for the second half at London Stadium.
French forward Martial was forced off the pitch after 62 minutes and was replaced by Juan Mata.
Solskjaer confirmed both strikers will undergo scans ahead of Tuesday's Champions League encounter with RB Leipzig, with United needing a draw to qualify for the last-16.
"It is unfortunate... sometimes you get muscle injuries. We lost Anthony and Edinson," Solskjaer told Sky Sports. "There's a game already on Tuesday. But It'll probably be (like this) this season.
"Some games we have to do without players and I'm glad we've got the substitutions we have."
After Tomas Soucek put West Ham ahead, goals from Paul Pogba, Mason Greenwood and substitute Marcus Rashford helped United clinch a fifth consecutive away victory in the league this season.
(Reporting by Hardik Vyas in Bengaluru; Editing by Clarence Fernandez)
