Alex McLeish has revealed Birmingham midfielder Alexander Hleb was "embarrasssed" when left out of the starting line-up for the recent shock win over champions Chelsea.
But the Blues boss has stressed no player has a divine right to be part of the team whatever their quality or reputation.
Hleb has struggled for full fitness since arriving in late August on loan from Barcelona.
He was restored to the side for Saturday's 1-1 draw against Fulham and gave one of his better performances before suffering a hamstring injury.
McLeish said: "I've repeatedly told him (Hleb) that he is not fit enough to start games.
"He was disappointed not to start against Chelsea.
"He thought it was a slight and was a bit embarrassed by that.
"A top player thinks he can just walk into the team - but it doesn't work like that."
McLeish is also demanding more aggression from £6 million summer signing, striker Nikola Zigic, and believes there are signs of improvement from the Serbian international.
The former Scotland boss said: "For such a big guy, the aggression is not in his game.
"He is a passionate guy but we've tried to put aggression in his game and he is getting better.
"It is about telling him to attack the ball because in Europe he probably only heads the ball three or four times in a game, and it's the same with Serbia.
"He is used to the ball being played on the deck but we want him to become more aggressive."