Birmingham boss Alex McLeish admits Roger Johnson and Scott Dann were not his first choice as a defensive pairing this season but is delighted with their progress.
McLeish initially looked to bring in centre-backs with Premier League experience following last season's promotion but was priced out of the market so turned to the Championship.
Johnson soon established himself in the Blues line-up after arriving from Cardiff, while injury problems mean former Coventry man Dann has had to wait until the last month to make his mark.
The pair have quickly looked at home in the top flight and have helped Birmingham gain four points from their last two games against Sunderland and Manchester City.
They face another tough test when Blues face Liverpool at Anfield on Monday but McLeish has plenty of confidence in his players.
He said: "I am not surprised how well Johnson and Dann have done. I think it shows we felt our homework was right about the players.
"I have to admit we did look at centre-halves with Premier League experience but, in the end, it was too expensive.
"I turned to the centre-halves whom I believed were as good as anyone, if not better, than anyone in the Championship in Johnson and Dann and they had that potential in them to do well.
"With the type of mentality they have got, they are winners. They will throw themselves at the ball on the edge of the box. You saw the bravery of Roger against Manchester City last weekend when he took a real painful knock in the throat.
"These two boys really want it. I know they want it, want to do well, learn and succeed, and there is a lot ahead of them.
"But they know the real proof of the pudding is if we retain our Premier League status and they've both been a big part of achieving that, in being mainstays and the rocks around which we've built the team.
"Then they will know they've arrived as Premier League players - but I've been pleased with them so far."