Wayne Rooney is likely to feature in Manchester United's UEFA Champions League tie with Sporting Lisbon, but Mikael Silvestre is expected to be out for several weeks.
Sir Alex Ferguson resisted the temptation to pick Rooney against former club Everton on Saturday, with the striker only back in training for a week after a foot injury.
But Ferguson admits the England international should be involved in the club's opening Champions League group game with Sporting on Wednesday.
"He will be fit for Wednesday, we have taken medical advice and he only started training on Monday," said Ferguson.
"And after only five days he is a bit short of fitness, he trained today and will train again tomorrow, and through until Wednesday."
But Silvestre is likely to miss the Sporting test after being stretchered off in the first half of the 1-0 win at Goodison Park.
The French defender appears to have suffered ligament damage in his knee, with Ferguson awaiting the results of a scan.
"We will send him for a scan now, but it didn't look good to me," added Ferguson.
"Our medical people are looking at it now. It looks like it's his knee that is hurt.
"We're getting a few (injuries) at the moment, but we will just have to get on with it."