West Ham United boss Sam Allardyce insists they're capable of upsetting Manchester United.

Allardyce admits West Ham will face a big task if they are to win tomorrow, but he takes comfort from the fact that the days of regular shut-outs at Old Trafford are now rare.

"Manchester United have leaked a few more goals than normal," Allardyce said.

"Their defensive qualities haven't been as good as they have been over the past few years.

"The problem is at the other end they never stop scoring goals, but if we can get our defensive unit on song and if we play as a team in and out of possession then you never know what will happen."