Former City star Rodney Marsh has expressed concerns over Toure's body language.
Marsh claims Toure 'didn't look interested' during Sunday's 1-0 defeat at Sunderland which left the Blues six points off the pace in the Premier League title race.
Rodney Marsh: "People close to Manchester City tell me Yaya Toure is not very happy and he's one of their great players.
"When you start to hear rumblings from within the camp, and you see the way Toure played last weekend, when he was strolling around and didn't look interested, I'm wondering now if it will all go a little bit the other way.
"It looks like they're throwing billions of pounds at players but keep coming up short. I think this season could end in tears at Man City."
Yaya Toure posted on Twitter: "Hey buddies, don't listen to the rumors [sic], I'm happy at city..the Toure brothers are in Casa and are missing Manchester."