It's reported that the Colombian striker is doing so to protect against aggravating the serious knee injury suffered in January that forced him to miss the World Cup.

The news raises further concerns about his on-going fitness.

Since joining Manchester United on loan from Monaco, Falcao has featured in just five games and found the back of the net only once. The deadline day signing was hailed as the deal that could revive United's fortunes, however the club's struggles have continued from last season, with Louis van Gaal's side currently seventh in the Premier League, 13 points adrift of leaders Chelsea.