Toure turned his ankle towards the end of the first half and it quickly became apparent that the Ivorian would not be able to continue.
Toure had to be helped back to the City dressing room and played no further part in the game.
The injury initially looked serious, but Mancini insisted that the damage was not too bad.
"We will have to see but I hope he will have recovered in three or four days," the Italian said.
"He fell over the other player's foot and hurt his ankle, but hopefully he will be OK."
Mancini will be a relieved man if the initial assessment proves to be correct given Toure's importance to the City cause.
In addition, even as Carlos Tevez is preparing for a new phase in his career, a new striker was emerging in John Guidetti, who equalised for City before Shaun Wright-Phillips slammed home a late winner.
"John is young. He is a good player and I think he can have a good future at Manchester City," Mancini added.
"He is strong. He is a typical English striker, even though he is Swedish. He has a good technique. He wants to improve.
"He will have time here. It is important that he continues to work well and continues to improve.
"Today he scored a good goal but when you are a young player, you need to improve every day. This year is important. He has a chance."