Manchester United striker Wayne Rooney re-injured his right ankle against Bayern Munich on Wednesday, a week after being hurt in the first leg.
Manager Alex Ferguson gambled on Rooney's fitness despite initially being ruled for up to three weeks, and the England international is in doubt for Sunday's Premier League match against Blackburn.
"I don't think he will be in contention on Sunday (against Blackburn)," Ferguson said. "But he should be available the week after (against Manchester City.)"
Rooney helped United lead 3-1 at Old Trafford but was forced off at the start of the second half. Arjen Robben's late volley reduced the deficit to 3-2, which sent Bayern through on away goals with a 4-4 aggregate score.
"It's similar to what he had last week. It's a burst blood vessel just below the ankle joint. He won't be out for too long," Ferguson said. "He's unlucky he went over on it. He had a couple of challenges and I don't think he got any protection (from the referee).
"He had a training session with us yesterday and he was very impressive. The medical people thought there was no danger. The fact he has gone over on the ankle is unlucky."
Without Rooney, who has scored 34 goals this season, United lost 2-1 to Chelsea and was overtaken by its opponent at the top of the Premier League.
Having relegated Dimitar Berbatov to the bench, Rooney helped set up Darron Gibson and Nani's goals inside the opening seven minutes.
But Rooney limped at times during the first half and only played 10 minutes of the second before being replaced by defender John O'Shea shortly after right back Rafael da Silva was sent off.
"There's no risk as it was a soft tissue injury, not ligament damage," Ferguson said before kickoff. "So that allows us to play him without worry of a recurrence."
United has only five Premier League matches left this season to overhaul Chelsea if it is to add to its League Cup title this season.
