The French striker, who has joined on a season-long loan from QPR, sustained a leg injury at his parent club and will not come up for the clash with City on August 19.
"When we've assessed him it looks like he'll have to have another couple of days before he can really do any work.
"I think his chances of starting at Manchester City are very very slim.
"Hopefully we'll cram as much as we can into him and get him up to speed. I think it's fair to the other players that he needs to be at their level before he pitches in."