The Dutchman came on late to provide the Red Devils with a crucial leveller on 90 minutes, securing a 2-2 draw at Upton Park and ensuring United earn a replay at Old Trafford.

Van Persie successfully latched onto a Ryan Giggs long pass before crashing home a thunderous equalizer past Jussi Jaskelainen in the West Ham goal.

Ferguson has praised the Dutchman's performance after coming on, claiming that his presence gave an element of maturity to the Manchester United attack.

"He's at a mature age now." he told reporters.

"He's brought that maturity to our front line, and his performance after coming on was tremendous."

Asked if he lost hope in Manchester United's ability to grab a late equalizer against West Ham, Ferguson admitted he never loses hope in his squad.

"You never do that with our team," Ferguson said.

"When you're 2-1 down with a couple of minutes left you just hope you get a break, but the manner of goal - the pass from Ryan Giggs and first touch from Robin van Persie and his finish - is absolutely world class, absolutely fantastic."