London - Individual battles are sure to be key to the outcome of Wednesday's Champions League semi-final, first-leg clash between Manchester United and Arsenal at Old Trafford, and United defender Nemanja Vidic knows he will be in for a tough time against Arsenal's front line. The Serbia defender has been a vital cog in United's march toward multiple honours this season and the defending champions will need him to be at his best to quell an Arsenal side that has arguably the best in England over the past two months.

London, Apr. 9 : Serbian defender Nemanja Vidic has said that Manchester United is guilty of complacency and warned his team mates that they must rediscover their focus if their season is not to end in failure.

In less than four weeks United have seen a seven-point lead at the top of the Premier League cut to just one and face a battle to reach the Champions League semi-finals after a 2-2 draw with Porto at Old Trafford.