Wayne Rooney must prove his fitness over the next 48 hours if he is to have any chance of starting for Manchester United in their Barclays Premier League title decider away to Wigan Athletic on Sunday.

Sir Alex Ferguson has expressed his confidence that Rooney will be fit to play against Wigan, having missed United's past two matches with a hip injury, but, unlike Nemanja Vidic, the England forward has not resumed full training and was involved only in a light session at Carrington yesterday morning. Rooney is said to be desperate to play some part at the JJB Stadium, but with a Champions League final to follow against Chelsea in Moscow ten days later, the 22-year-old may sit out the final Premier League fixture or at best be named as a substitute in case United are in urgent need of inspiration in the closing stages.

United go into the final day of the Premier League campaign level on points with Chelsea, albeit with a superior goal difference, but the climax of the season will unfold to a backdrop of tension between the clubs over the fallout from their meeting at Stamford Bridge on April 26. The FA has given both clubs until today to submit their observations on the post-match fracas between some United players and members of the Chelsea groundstaff amid allegations that racist remarks were aimed at Patrice Evra, the United full back.

Evra was involved in a fight with Sam Bethell, the Chelsea groundsman, as he and his team-mates took part in their post-match warm-down, with Tony Strudwick, the United fitness coach, and one of the club's players having alleged that Bethell made a racist remark. Bethell has strongly denied this claim and Chelsea have stood by him, but that allegation is understood to have been included in United's submission to the FA, even though Evra has said that he was not aware of such a comment being made.

The FA will scrutinise the observations of the clubs before deciding what, if any, action to take against any of the individuals involved, but it is thought unlikely that any hearing would take place before the Champions League final on May 21.

Several Chelsea players have expressed concerns that Wigan may be demotivated for their match against United, having already secured Premier League survival, but Marcus Bent, the forward, has promised Avram Grant's team that they will play fair. “There have been something like ten or 20 people randomly coming up to me in the street, asking me not to try and to take it easy and let United win the game,” Bent said. “But we are professionals and we are all going into the game on Sunday wanting to get three points.”