Patrice Evra was inevitably greeted by boos and chants after the Luis Suarez debacle but despite the negativity thrown that way, United still dominated the ball.
However, it was Liverpool that opened the scoring in the 21st minute and in front of the United fans too.
But the Red Devils’ persistence paid off not long after. Ji-Sung Park put the ball past keeper Pepe Reina into the bottom right corner of the net from only eight yards out in the 39th minute.
The second half seemed a near repeat of the first. United continued to control the midfield, and Liverpool was giving the ball away too much for comfort. Manager Kenny Dalglish made some changes in the 63rd minute including Charlie Adam on for Dirk Kuyt and Dirk Kuyt for Jamie Carragher. Later, Craig Bellamy would replace Steven Gerrard. After all of the subs were made only then did United begin to falter. Alex Ferguson tried to avoid the prospect of a replay by also making changes including Berbatov for Ryan Giggs and Hernandez for Paul Scholes.
And it was Dirk Kuyt who saved the trouble of a possible replay at Old Trafford. In the 88th minute, the Dutch international easily blast the ball past United keeper David De Gea from a pass off of Andy Carroll. Anfield naturally filled with deafening roars of cheers.
Dalglish spoke highly of Kuyt and the rest of the team’s efforts after the match.
“For Dirk it's a fantastic day and it's a great day for us to go through to the next round of the FA Cup,” he said. “To beat Manchester United is a great achievement for everybody.”
Liverpool will now face Brighton and Hove Albion in the fifth round.