Aston Villa defender Olof Mellberg is struggling to be fit for Saturday's clash with Manchester United.

The Sweden centre-half has suffered a back injury while on international duty and looks certain to miss the Euro 2008 qualifier with Northern Ireland.

Villa boss Martin O'Neill is facing an anxious wait to discover the full extent of the injury. Mellberg has been deputising at right-back after the sale of Aaron Hughes to Fulham and the retirement of Mark Delaney.

If he is ruled out, then Craig Gardner - a midfielder - may revert to the role he occupied for the opening four games of the campaign.