The club have said he will undergo a minor procedure in Portugal this Friday, and be out for four to six weeks.
The ex-Liverpool striker has scored his first goal for Barcelona.
We take a look at two Manchester United players who could leave Old Trafford before loan window closes.
Hatem Ben Arfa's efforts on loan at Hull City are struggling to match those of Remy Cabella, a man brought in to replace him at Newcastle United.
Gylfi Sigurdsson may be impressing at Swansea, but Tottenham Hotspur have reason to be positive thanks to the form of Alex Pritchard on loan.
Blackburn Rovers manager Gary Bowyer underlines the role played by Luke Varney in the win against Leeds United in the Championship on Saturday.
West Ham United defender James Collins says that manager Sam Allardyce wants the team to bounce back from the defeat to Everton in the Premier League.
Chelsea qualified for the Champions League knockout phase with a group match to spare after an emphatic 5-0 win over Roberto Di Matteo's Schalke side in Gelsenkirchen.
Former Arsenal and Chelsea striker Nicolas Anelka says missing out on a permanent move to Liverpool is his biggest career regret.
Mirco Antenucci says other than the Italians at Leeds, Alex Mowatt has impressed him the most.