Manchester City manager Manuel Pellegrini has revealed that the club is waiting to discover the extent of Yaya Toure's hamstring injury.
The midfielder was substituted at half time during City's 3-2 win over Aston Villa in the Premier League on Saturday.
Ivory Coast international Toure is now expected to undergo a scan to determine how bad the damage is.
"Toure had a hamstring problem so he couldn't play the second half," Pellegrini told reporters after the game.
"It is difficult to know today what happened, but it was not a precaution. It was a muscle injury and we will see tomorrow [Sunday] or Monday how bad it is."
City continue the defence of their league title on May 3 when they face Tottenham Hotspur at White Hart Lane.
