Nani is an injury doubt for Sir Alex Ferguson's side when they take on Liverpool in the FA Cup fourth round match at Anfield this Saturday.
The Portuguese winger is expected to be sidelined for two weeks with a foot injury but there are growing fears that the player could have snapped a metatarsal, according to the Daily Mail.
The Red Devils star is believed to have been spotted leaving the Emirates on Sunday wearing a protective boot following United's 2-1 win over Arsenal.
Nani could join Rio Ferdinand on the sidelines, who may also be unavailable with a back injury.
