Birmingham City have made a significant attempt to ward off the Premiership's bigger predators by tieing up prize asset Colin Doyle on a new four-year contract.

The giant Republic of Ireland goalkeeper has been rewarded for his consistent form since breaking into the Blues team in February with a new four-year deal which will bind him to St Andrew's until 2011.

Doyle admits that he has Blues goalkeeping coach Nigel Spink to help for his big breakthrough.

"I arrived here when I was about 15 and Nigel has been there for the whole six years working with me," said Cork-born Doyle. "To be honest, he's the main reason I'm in the team.

"If you ask him, he'll tell you that when I came over here, I was just this mass of raw ability with no proper goalkeeping training behind me.

"But Spinky has turned me into the keeper I am today really. We get on extremely well and there is a lot I have to thank him for."

Apart from tabloid speculation linking him with Arsenal, Doyle's form has not gone unnoticed by Republic of Ireland boss Steve Staunton who included him in his squad for last month's Euro 2008 qualifiers with Wales and Slovakia.

Though his manager Steve Bruce is not surprised that his recent form might have attracted interest from higher up, Doyle is intent only on reaching the Premiership with Blues.

"I'm delighted to have broken into the team," he said, "and I want to win the Championship and establish myself as No 1 at Birmingham for many years to come.

"All the focus at the moment is on getting the club into the Premiership because this is where this club deserves to be."

Doyle has been working with Spink — a European Cup winner 25 years ago with Second City rivals Aston Villa — since joining Blues as a 15-year-old in 2001.

He has had to bide his time out on loan with short spells at Chester City and Nottingham Forest and last season at Millwall. But, after being brought in to replace Maik Taylor against Colchester, he has not looked back.

His new-found stature was evident in the latter two of the three straight wins that have taken Blues to the brink of a return to the Premiership. At Leicester ten days ago he made a handful of genuine match-winning saves, and then he saved his side from defeat at Molineux on Sunday, capped by an injury-time penalty save.

Doyle can expect to be kept busy when in-form Sheffield Wednesday arrive at St Andrew's tomorrow looking to keep their own promotion challenge bubbling on the back of a run of five straight wins.

If Sunderland lose at home to Steve Cotterill's Burnley tonight, Blues can be promoted tomorrow. But, otherwise, it is simply a question of trying to claim a fourth straight win and hoping Derby County slip up at Crystal Palace on Sunday, or else it will go down to the wire the following Sunday.

Bruce knows a lot depends on how his old team-mate Roy Keane's Sunderland respond to their shock defeat at Colchester last Saturday.

"We had exactly the same over Easter," said Bruce. "I know how Roy felt.

"Losing to Burnley and Barnsley over Easter was a real kick in the teeth. But thankfully the team have responded. We've dusted ourselves down and it's now all to play for with two games left.

"We were five points behind Sunderland after Easter, now we're on top. That's how quickly it changes."