The Belgian defender has missed the past month with a groin injury but is being given the opportunity to prove he is available for Tuesday night's Champions League clash with Viktoria Plzen in the Czech Republic.
However, if he does not come up, Pellegrini insists he will not take any risks with the City captain.
"I think he will be 100 per cent, but if not then he won't play," he said.
"This is an important match and we have a lot of good players, so I won't select players who are not 100 per cent fit. We'll talk to the doctors and decide tomorrow.
"Vincent is a very important player for us. He's been injured for a month but without Vincent the defence has played well, except for the game against Cardiff. They have had three clean sheets. We have other players if anyone is not 100 per cent."