Alou Diarra insists that “anything can happen” in West Ham’s FA Cup third-round replay against Manchester United.

After Robin van Persie’s late equaliser had denied Sam Allardyce’s men from progressing to the fourth round at the first time of asking, the Hammers followed up the 2-2 draw with a disappointing 3-0 defeat against struggling Sunderland in their last Premier League outing.

While the France international is under no illusions that West Ham will have to raise their game if they are to win at Old Trafford, Diarra insisted that an FA Cup shock is possible.

“It’s not going to be easy in Manchester,” Diarra told the club’s official website. “They’re in confident mood, even if they make a few changes. They have strength in depth and a lot of players and can rotate.

“For us, it’s a question of raising our game in comparison to our performance at Sunderland and start the match just as we did in the home game.

“It’s not an easy game but in the cup anything is possible. We’ll have chances at Old Trafford.”