Rio Ferdinand has been told to prove his fitness at Hull on Sunday - or face the prospect of missing out on the Champions League final in Rome.
United manager Sir Alex Ferguson has warned his captain that he may miss out on a starting place against Barcelona if he cannot overcome his calf injury.
The England centre-back has missed the last three matches since sustaining the injury in the Champions League semi-final second leg victory over Arsenal at the Emirates on May 5.
Ferguson is optimistic the 30-year-old will be available for Sunday's final Premier League match of the season at Hull as that will prevent him having to make a difficult decision in his team selection to face Barcelona in Rome next Wednesday.
"I am hoping he will be fit for Sunday, if not he is doubtful for Wednesday that is for sure," said the United manager.
"I think he needs a game going into the Champions League final because him having not played for three weeks is too much.
"The plan is for him to start training with us tomorrow and once we get football training we will have a better idea of his availability for Sunday.
"I think he is probably fit to play Wednesday but whether I would start him without a game is another matter."