The Sunday Mirror says Guidetti has been struck down by a mystery illness that has left him with no feeling in his right leg.
Guidetti, who only wants to return to City if he's in the first team, is hoping that the problem doesn't keep him out of Euro 2012.
Feyenoord doctor Casper van Eijck said: "I cannot give guarantees about Guidetti's comeback in football.
"It looks like some virus has got hold of him. You can't treat a virus with medicines. He needs a lot of rest.''