A medical could cost Manchester City the title, fears manager Roberto Mancini.

The Sun says Sergio Aguero had a knock that was initially only going to sideline him from last Saturday's game at Stoke.

But a spray on the injury resulted in an allergic reaction, causing the foot to balloon and blister as if it had been burnt.

Aguero, 23, misses today's game with Sunderland and it is unclear for how long he will be out.

Boss Mancini did not want to be drawn on what happened but said: "It is impossible we can lose a player to a stupid situation.

"It is just a stupid injury. It didn't happen at home, it happened here."