Villa manager Gerard Houllier has confirmed defender Curtis Davies has completed his move to Birmingham in a deal which could be worth up to £2.5million.

Davies follows in the footsteps of Liam Ridgewell and Craig Gardner to make it a trio of players who have moved directly between the bitter Second City rivals.

Blues manager Alex McLeish was keen to add a defender to his squad before the transfer window closes, with Scott Dann ruled out for the remainder of the campaign with a hamstring injury.

And Davies will join in a deal which will initially be worth £1.75million, rising by an additional £750,000 based on appearances and other clauses.

But Houllier insists it’s a straight deal for Davies and it does not involve any kind of swap for Sebastian Larsson.

The Villa boss said: “Curtis had the option to go to Leicester or to Birmingham and he has opted for Birmingham. I think he is sold.

“He is a nice lad but as you know we have four centre-backs in James Collins, Richard Dunne, Carlos Cuellar and Ciaran Clark. He was not getting enough time to play.

“With Larsson, it is far from being done. That is all that I can say. It is a separate deal.”

Stephen Warnock’s hopes of returning to former club Liverpool on loan also hang in the balance after Villa insisted on the defender’s wages being paid in full by the Merseyside club.

The 29-year-old left-back has been training with Villa’s reserves and has not featured since the 4-0 defeat to Manchester City.

Liverpool manager Kenny Dalglish has played Glen Johnson at left-back and had hoped to bring Ormskirk-born Warnock back to Anfield.

But Villa will only allow the player to leave if Liverpool pay a stipulated loan fee and foot the cost of Warnock’s reputed £40,000 per week wages.

Elsewhere in Villa’s defence, Houllier will give fitness tests to defensive Ciaran Clark and Kyle Walker ahead of the FA Cup game with Blackburn.

Versatile defender Clark has missed the game against Wigan with a hamstring problem, while on-loan Tottenham right-back Walker has set out the last two matches with a back injury.

Luke Young, Fabian Delph and Stephen Ireland are all still nursing knee injuries and will not be considered for the fourth-round tie.