Manchester City boss Mark Hughes fears Joe Hart may have played too much football too soon.
Hart is currently on-loan at Birmingham City and has hinted at making the move permanent.
Hughes said: "Joe Hart is still our player, of course, and we still have a huge regard for his ability. But there have been too many examples when goalkeepers have shone at the start of their careers and then faded.
"They get damaged because they have been in the first team too long too early in their career and haven't been able to recover when things have gone wrong.
"We didn't want that to happen to Joe. We still have huge hopes that he will be a top goalkeeper for Manchester City in years to come.
"We were at the stage when we needed an experienced goalkeeper. That's why I signed Shay Given."