Wayne Rooney will miss Manchester United's Premier League game away to Blackburn Rovers on Sunday after re-injuring his ankle in the Champions League quarter-final exit against Bayern Munich on Wednesday.
The striker, whose 34 goals have underpinned United's title challenge, lasted 55 minutes against Bayern after making a surprisingly fast return to action, just a week after damaging ankle ligaments in the first leg.
"I don't think it's as serious as we said the first time, but I think he'll be ready for the (Manchester) City game," manager Sir Alex Ferguson told the club website on Friday.
"We've got more time to work on it, anyway. Other than that everyone else is fit."
Arsenal's injury-hit squad could soon be boosted by the return of Dutch forward Robin van Persie, who is set to return from ankle ligament damage sustained in November.
"Robin will be joining the squad for full training imminently," physio Colin Lewin told.
Arsenal, who travel to London rivals Tottenham Hotspur on Wednesday, also said that injured defenders Kieran Gibbs and Johan Djourou were both expected to return to training within the next fortnight.
Manchester City defender Joleon Lescott could be out for another month as he recovers from a tear to his hamstring tendon, the club said on Friday.
World Cup hopeful Lescott, who has already missed 12 weeks of the season after knee surgery, is using an oxygen chamber to try and speed his recovery.
City, who are favourites to finish fourth, are also likely to be without Micah Richards for Sunday's clash with Birmingham City because of a knee injury.
Versatile Pablo Zabaleta is still suspended. Left back Wayne Bridge is rated at 50-50 by manager Roberto Mancini.
Struggling West Ham United will be without suspended influential midfielder Scott Parker for Saturday's match at home to Sunderland.
The Hammers, without a win in seven matches, are waiting on the fitness of midfielders Valon Behrami and Alessandro Diamanti, the club said on its website.
Sunderland duo George McCartney and Andy Reid are struggling with hamstring troubles while John Mensah is doubtful with a knee problem.
Young striker Louis Moult could be selected for 10th-placed Stoke City's match at Wolverhampton Wanderers on Sunday if club top scorer Ricardo Fuller does not feature.
Fuller, who has eight goals this season in all competitions, is struggling with a knock and is also one booking away from a two-match suspension.
"If he doesn't play, then Louis will come in for him. The lad has done very well in the reserves this season," Stoke manager Tony Pulis told the club website.
