City boss Kevin Keegan believes the French striker feigned injury because he wants to leave the club.
"We need everybody fit right now and I put players out against Arsenal who were not 100% fit, but Nicolas wasn't one of them.
"He didn't even feel he could take a fitness test, which I was disappointed with.
"I don't think there is any doubt that if someone came in with a really serious bid for Nicolas, we would sell him. I'd use the money to strengthen other parts of the team.
"Everybody knows we still have £5m to pay on Nicolas, so you would have to add quite a bit more on to that figure for us to sell."