Arsenal legend Martin Keown believes Liverpool ace Fernando Torres has a psychological edge on Manchester United's defenders Rio Ferdinand and Nemanja Vidic. Torres faces United tomorrow at lunchtime at Old Trafford.

Keown told the Daily Mail: "United's defensive pairing of Nemanja Vidic and Rio Ferdinand clearly have the ability to deal with him, but something is not quite right with their technical and psychological approach when they line up against the striker.

"Back in October at Anfield, Torres out-paced and out-muscled Ferdinand to score Liverpool's opener in a 2-0 win. At Old Trafford last season it was Vidic who paid the price for letting the ball bounce over his shoulder when Torres nipped in and raced away to equalise in Liverpool's 4-1 demolition.

"Dealing with Torres is the collective responsibility of the back four. But it is Vidic's performances that have suffered most in these head-to-head duels - he has been sent off in his last three meetings with Liverpool.

"He has allowed the threat of Torres to mushroom in his head and he cannot afford to allow this to happen again."