The Northern Ireland stopper, 38, who played second fiddle to Joe Hart last term, recently signed a one-year extension at St Andrew’s.
He is fully expecting to be Foster’s understudy but is ready for the challenge to oust his new team-mate as he looks to remain in the international set-up.
Speaking to reporters, he said:“I imagine Foster will start the season as first choice so it will be up to me to push him and hopefully get in and get a few games.
“If he produces the level of performance of which he is capable – similar to Joe Hart last season – it’s going to make things extremely difficult for me.
“If I am not getting many games at Birmingham it’s going to be difficult with Northern Ireland, but I am up for the challenge.
“If I am not producing the goods and someone is there who’s playing well regularly for their club, then I’m sure Nigel Worthington would make the change.
“I am still enjoying the game and I love being involved with Northern Ireland so retirement is a long way off yet.
“So hopefully I will keep performing at the level I know I can and help Northern Ireland qualify for Euro 2012.”