Manchester United's injury list has added yet another name after winger Antonio Valenica was seen leaving the training ground on crutches.

The Daily Mail has reported that Valencia was spotted leaving United's Carrington training ground on Wednesday wearing a protective boot on the same day that defender Nemanja Vidic was ruled out of action for eight weeks.

Antonio Valencia
Valencia being challenged by Glen Johnson [Reuters]

United already have a number of first team players sidelined and are struggling at the back where Phil Jones and Chris Smalling have left Sir Alex Ferguson with very few options.

Rio Ferdinand missed the opening game of the season due to injury and in the last few seasons has struggled with numerous ailments which have ruled him out of action.

Fellow centre-back Jonny Evans has only just returned to the first team after his injury, leaving Ferdinand and the 24-year-old as Ferguson's only senior options.

Perhaps the biggest loss is that of Vidic who is the club captain and an instrumental figure at Old Trafford. United have often struggled when he has been out of action, with the Mail pointing out their win percentage drops by nearly ten per cent when he is absent.

The Serbian centre-back will miss four of United's five Champions league group games and could be ruled out of at least eight Premier League fixtures.

With problems in defence, the last thing Ferguson needed was for an attacking player to be ruled out of action. While Valencia has filled in at right-back, he is always an attacking threat and was used on the right-wing against Liverpool last weekend.

There has been no official statement from United on the severity of the injury but the Mail believes he picked up the injury when being challenged by Glen Johnson and winning a penalty.

United already have some concerns in attack as Wayne Rooney is still out of action due to the deep gash he suffered at the start of the season, while Ashley Young is unlikely to return from his knee injury until the end of next month.