Manchester United boss Sir Alex Ferguson expects Wayne Rooney to be out for around three weeks, after the striker suffered a hamstring injury during Wednesday night's 1-0 win over Wigan Athletic.
Rooney put United ahead in the opening minute at Old Trafford but not long afterwards limped to the sidelines and was immediately replaced by Carlos Tevez.
''It is a hamstring injury,'' Ferguson confirmed. ''That will be about three weeks. We hope it is no longer.''
It is not the only problem United face either as Ferguson reported both Tevez and Jonny Evans completed the game despite taking heavy knocks during the first half that will have to be assessed ahead of Saturday's trip to Bolton.
''Carlos limped through the second half and Jonny limped through virtually the whole game,'' revealed Ferguson.
''We will have to assess them and see how they are. We need our best team on Saturday because Bolton are a big side.''
United's victory was built on the back of a ninth successive Premier League clean sheet, a run that stretches to their defeat by Arsenal at the Emirates Stadium at the beginning of November.
Yet Wigan made their hosts battle every inch of the way, drawing warm praise from Ferguson.
''Wigan are the best side that has played here this season by far,'' said Ferguson, who anticipated a harder contest than the one Chelsea provided on Sunday.
''It was an outstanding performance from them. They really made us work. They are a very positive team.''
Ferguson felt United would have made it easier for themselves had Tevez taken an opportunity midway through the opening period when he strode onto John O'Shea's header.
However, while the South American skipped round Chris Kirkland the angle would have been too tight for him to finish anyway, even without Titus Bramble's excellent tackle.
Still, the win means the gap to leaders Liverpool has now been narrowed to just two points.
And, as Anfield does not host the Merseyside derby until Monday, three points at Bolton on Saturday will take the Red Devils top.
''I don't mind when we go top but I always feel it is the best position to be in,'' said Ferguson, who picked Nemanja Vidic as his star man.
''Hopefully we will be there by Saturday night, so we need to try and patch the injured players back up.''
As Rio Ferdinand and Patrice Evra are already missing, Ferguson will cross his fingers Evans makes it, otherwise he will be forced to play Gary Neville in central defence or John O'Shea, who would leave a selection problem at left-back if he was switched inside.
Ferguson does have more options up front should Tevez be sidelined, with Danny Welbeck offering an orthodox alternative and Cristiano Ronaldo and Ryan Giggs giving United different options to partner record signing Dimitar Berbatov.
Wigan boss Steve Bruce has an altogether different problem in front of him after chairman Dave Whelan confirmed Tottenham had made a bid - believed to be £10million - for midfielder Wilson Palicios.
''They are not the only ones either,'' reflected Bruce. ''There is one from Spain and another from Germany.
''To be fair we only received the Tottenham one at 8pm last night when I got a call from our chief executive.
''I have not even had a chance to talk with the lad yet but he has only enhanced his reputation with his performance here tonight.
''In two years' time Wilson will be as good a midfielder as there is.''
As someone who left Gillingham and then Norwich in a career that took him to Manchester United, Bruce knows exactly how Palicios will be thinking. And, while he does not want to lose the Honduran, the Latics chief accepts it may be inevitable.
''We will have to see what develops in the next 24 or 48 hours and what Tottenham are prepared to go to,'' said Bruce.
''The thing is when they agree to come to Wigan we sell these lads a dream. I have been there myself. How do you deny someone like that.''