Manchester United manager Sir Alex Ferguson has expressed his relief as his side salvaged a 2-2 draw at West Ham United in the FA Cup on Saturday.

Robin van Persie came off the bench at Upton Park to grab a 90th-minute equaliser for the Red Devils in their third-round tie against the Hammers.

"You never rule out fighting back with our team but certainly at 2-1 down with a couple of minutes to go you hope you get a break," Ferguson told ITV Sport.

"The manner of the goal with Ryan Giggs's ball and Robin van Persie's finish was world class."

The two sides will both be in the hat for Sunday's fourth-round draw, which takes place at 3.30pm.