Dirk Kuyt pounced two minutes from time to give Liverpool a narrow victory over fierce rivals Manchester United.
With the scores level and an Old Trafford replay on the cards, Kuyt latched on to an Andy Carroll flick-on to fire past David De Gea and send the Reds into the fifth round of the FA Cup.
Much of the pre-match build-up centred around the Luis Suarez-Patrice Evra racial spat and how both clubs would react in what was their first meeting since the clash. But, despite the inevitable banter between the opposing supporters and booing of the United's captain every touch, the game passed without major incident.
With only 2 full days rest since Wednesday night's impressive performance against Manchester City which saw the Reds reach the Carling Cup final, Kenny Dalglish freshened his side up bringing in Martin Kelly, Maxi Rodriguez and Andy Carroll, whilst there was also a surprise start in midfield for Jamie Carragher. For United, Sir Alex Ferguson was unable to call on a host of injured stars, including Wayne Rooney, Nani and Phil Jones. But despite still having the likes of Dimitar Berbatov and Javier Hernandez at his disposal, the Scot chose to go with Danny Welbeck up front on his own, instead packing the midfield with Ji-Sung Park included.
As is so often the case when these two sides meet, the first 20 minutes were cagey, with only two real sights of goal. Maxi's 20-yard shot forced De Gea into a good save low to his right, whilst Antonio Valencia struck an upright after cutting in from the right.
But on 21 minutes, the home side took the lead. After Stewart Downing had done well to nip between two defenders down the right, the ball eventually fell to Jose Enrique, whose long-range effort was deflected behind by a United defender. From the resulting corner, United's Spanish keeper found himself bullied by the physical presence of Carroll and Kelly, which allowed Daniel Agger to climb highest and nod into the net.
Finding themselves behind, United started to dominate possession, with veteran Paul Scholes in fine form. After not really creating any attempts, the visitors were given a helping hand as they equalised six minutes before the break. When Valencia flicked the ball down the right, Liverpool left-back Enrique should have dealt with the loose ball, but instead he dallied, allowing United right-back Rafael to step in, get to the byline and centre for Park to clinically smash past Reina.
After the restart, United continued to see more of the ball. A fine through ball from Michael Carrick saw Welbeck knock the ball past the on-rushing Reina, only for Martin Skrtel to clear.
With the home crowd starting to get a bit restless as the Reds struggled to get into the game, Dalglish made a double substitution, bringing on Charlie Adam for Carragher and Kuyt for Maxi. The changes, Adam in particular, allowed Liverpool to assert more pressure, from which De Gea suffered more problems when he conceded a corner after failing to catch a straight-forward cross.
On 72 minutes, Carling Cup hero Craig Bellamy came on as the Reds looked to find a winner, although the sight of captain Steven Gerrard leaving the field raised some eyebrows. United's response was to throw on an attacker of their own in Hernandez, but their decision to take off the game's outstanding player in Scholes, meant United subsequently struggled to make any clear cut chances.
With the game heading towards a replay, Liverpool struck with only two minutes remaining. When Reina's goal-kick was flicked on by Carroll, who had enjoyed one of his better performances in a red shirt, Kuyt got in behind the sleeping Evra, to fire home past De Gea and send the Kop into raptures.
Within a minute, the lead was nearly extended as Enrique's cross was headed onto the bar by Carroll, with Kuyt prodding the rebound narrowly wide. United's last throw of the dice was Berbatov, but the Reds safely saw stoppage time out to take their place in the hat for Sunday's fifth round draw.
After the debacle of last Saturday's defeat at Bolton Wanderers, the win capped a fine few days for Dalglish's men. Having dumped Roberto Mancini's City side out of the Carling Cup on Wednesday, the elimination of United from the FA Cup completed a fine double for the Anfield side.