Villa are closing in on the signing of Stephen Warnock as manager Martin O’Neill’s recruitment drive gathers pace.

The Blackburn left-back reportedly underwent a medical ahead of a potential £4million switch to the West Midlands. Villa are remaining tight-lipped, but the move could go through ahead of their Europa League qualifying tie against Rapid Vienna tonight.

O’Neill is desperate to bolster his defence after the retirement of Martin Laursen, the exit of Zat Knight and Wilfred Bouma’s long-term injury absence.

Former Liverpool man Warnock has been high on the managers’ wanted list and would become his fourth summer signing.

The 27-year-old’s arrival would push the summer spending to more than £24million after Stewart Downing, Fabian Delph and Habib Beye joined for a total of more than £20m.

O’Neill has also tabled a £2m bid with Portsmouth for Sylvain Distin and is believed to have agreed a £6million fee for Manchester City captain Richard Dunne.

Warnock, who has had loan spells at Bradford and Coventry, made 109 appearances for Rovers but came through Liverpool’s academy, playing over 50 games for the Reds, before a 2007 switch to Ewood Park.

He could be at Villa Park for the crunch clash with Vienna, with the hosts trailing 1-0 from the first leg.