Manchester United centre forward Radamel Falcao is resigned to his stay at Old Trafford being short-lived.

Sources close to the Colombian striker now convinced the 29-year-old simply joined the wrong club last summer.

Speculation about Falcao’s future has been rife as the South American has struggled during a loan spell from Monaco to recapture the form that made him a world superstar.

Radamel Falcao (centre) in action for the Manchester United Under 21 team on Tuesday

Striker Falcao (second right) has often been left on the substitute's bench at United

Falcao celebrates scoring against Leicester, one of only four he has scored for United since joining

But in the wake of being relegated to United’s Under 21 team on Tuesday night, it is understood Falcao realises that his dream of a long-term deal at United is over.

Falcao has scored only four times since he joined the club out of the blue on the final day of last summer’s transfer window.

He was taken off during the home win against Sunderland last month and has not played first-team football since.

Falcao (right) shakes the hand of United manager Louis van Gaal after being substituted

Falcao's last appearance for United came in the 2-0 home victory over Sunderland in the Premier League

Falcao (left) was said be shocked that he was asked to play for the United reserves on Tuesday

Sources close to him last night revealed his ‘total shock’ at being told to report for reserve-team duty on Tuesday night, just 24 hours after being left on the bench as United failed to rescue their FA Cup tie against Arsenal at Old Trafford.