Manchester United are waiting on the fitness of Robin van Persie after the Netherlands striker left Swansea's Liberty Stadium on crutches.
Van Persie, 31, also had a protective boot around his right ankle after suffering an injury in the final stages of his side's 2-1 defeat on Saturday.
But he could not be replaced as United had already made three substitutions.
"We dominated the game even with 10 men when Van Persie could not run any more," said United boss Louis Van Gaal.
Former Netherlands coach Van Gaal did not give any more details about Van Persie's injury after the match.
The striker, who has scored 10 goals for United this season, returned for the trip to Swansea after missing last week's FA Cup win at Preston with a minor knock.
But he could not prevent the Swans, who won 2-1 at Old Trafford on the opening day of the season, recording a first league double against the Red Devils.
The visitors led through Ander Herrera's low strike, but the hosts equalised within two minutes as Ki Sung-yueng swept in Jonjo Shelvey's cross.
Van Gaal's side could not find a second goal, despite dominating the second half, and were made to pay when Shelvey's 73rd-minute shot deflected off Gomis past away keeper David De Gea.
Defeat means United drop to fourth place in the Premier League, hampering their hopes of making an instant return to the Champions League after failing to qualify for Europe last season.