After a fairly even opening period, the game erupted into life when Rooney lashed home the opener from close range after Jordan Henderson could only manage to flick on Ryan Giggs' corner into the striker's path.
And within a couple of minutes, Rooney doubled United's advantage after Jay Spearing gave away possession to Antonio Valencia in the middle of the park, where the Ecuadorian proceeded to head straight for the Liverpool goal before sliding his team-mate through on goal.
Liverpool pulled one back when Luis Suarez pounced on a poor touch by Rio Ferdinand to lash home an effort past David de Gea, but the Spaniard then provided a brilliant save from Glen Johnson at the death to grab all three points for the Red Devils.
Here, ESPNSTAR.com takes a look at the movers and shakers from Saturday's game at Old Trafford.
David de Gea - 7.5
For the second week in a row, the young Spaniard, who has had his fair share of criticism this season, rescued United at the death.
With the Red Devils holding on to their one-goal lead, De Gea extended a strong hand to tip Glen Johnson's late effort over the bar, once again showing his aptitude for the spectacular.
Rafael - 7
Another lively showing from the Brazilian right-back, who is under pressure to perform especially with Phil Jones and Chris Smalling showing their versatility across the back.
Rafael completely shut Stewart Downing out in the first half, and regularly pushed forward to offer a spare man in attack. Nearly gave United the lead in the opening period when he cut in on his left foot and curled a shot which was well smothered by Reina.
Rio Ferdinand - 7.5
Was culpable for Liverpool's goal when he cushioned the ball into Suarez's path, but apart from that one error, Ferdinand had an excellent game, reading the game well and mopping up whenever his team-mates made errors at the back.
Jonny Evans - 7
Your typical display from the Northern Ireland international is not without the odd slip up at the back, but thankfully for United, his mistakes today didn't cost them the result.
Seems to enjoy putting himself under pressure, choosing to dwell on the ball rather than clear it first time, but still, he had one of his better showings today.
Patrice Evra - 7.5
Strong display from the Frenchman, whose game was somewhat tarnished by the pre-match drama between him and Suarez.
Hardly gave Dirk Kuyt a sniff of the ball, and regularly bombed forward to support forays forward.
Antonio Valencia - 8.5
Yet another brilliant game from Valencia, who has to be one of the best wingers in the Premier League at the moment.
Gave Jose Enrique a torrid time down the flank, and had a hand in United's second when he capitalised on a loose ball in midfield and played a perfect pass into Rooney's path.
Paul Scholes - 7.5
A majestic performance from Scholes and one wonders if Sir Alex Ferguson is secretly considering begging the veteran to play on for another season.
Kept possession well for United, and knew when to slow things down, and when to put the opposition on the back foot with a penetrating crossfield ball.
Michael Carrick - 7
A tidy-if-unflashy game from Carrick, who seemed happy to let Scholes dictate matters for United. Instead, the England international spent more of his time providing a shield in front of the Red Devils backline, a job he did considerably well.
Ryan Giggs - 8
The veteran Welshman rolled back the years with a scintillating display down the left, running at the Liverpool defence with intent and causing Glen Johnson a real headache.
Giggs also posed a threat from set pieces, and already Ferguson's decision to hand him a new contract seems to be the right one.
Danny Welbeck - 7
Welbeck toiled manfully all game long and while he failed to have an impact on the scoreboard, he did extremely well to hold up the ball in attack, especially considering he was often double-teamed by Martin Skrtel and Daniel Agger.
Wayne Rooney - 9
A clinical display from Rooney, who made the most of the only two real chances that he was presented with.
Latched on to a flick on from a corner just after the break and lashed home the opener past Reina, before calmly slotting past the Liverpool keeper a couple of minutes later after being played through by Valencia.
Could have grabbed a hat-trick when the ball was rolled into his path just inside the area, but he rushed his shot and was unable to find the target.
Pepe Reina - 7
The Spaniard produced a good reaction stop in the first half to keep Scholes' point-blank range header. Couldn't do much to stop Rooney's brace, and must have been wishing for more protection from his defence.
Glen Johnson - 6.5
Not the worst display from Johnson, but you get the feeling Kenny Dalglish was hoping he would have been able to contain Giggs more ably, especially considering the advantage he held over his opponent in both pace and strength.
Martin Skrtel - 6
A poor day at the office from the Slovakian. Failed to impose himself in aerial challenges, and allowed the United attackers too much space.
Daniel Agger - 7
Agger was the most capable of Liverpool's back four today, although that isn't saying much. Always looked comfortable on the ball, and tried to initiate attacks on a couple of occasions with long balls from the back.
Jose Enrique - 5
One of Dalglish's better signings this season yet plenty of question marks still remain over the Spaniard's defending, and he was severely exposed by Valencia today.
Was no match for the Ecuadorian's strength and pace, and was seen chasing Valencia's shadow for much of the game.
Jay Spearing (off 61') - 5
Tried his best to contain the United midfielders but was just lacking in that bit of quality. Still capable of doing his part as a squad member, but for now, he doesn't appear to have the necessary class to play in games of this stature.
Chose one of the worst places to give possession away to United, allowing Valencia to steam right through the middle and lay the ball off for Rooney's second.
Steven Gerrard - 7.5
One of Liverpool's best performers, although even the talismanic captain cannot do it all on his own every time. Was not afraid to put in a strong challenge in the middle of the park, and his distribution was neat as ever.
Jordan Henderson - 6
Hardly spotted throughout the game. Might probably have been a better idea for Liverpool to start with Adam.
Dirk Kuyt (off 75') - 6.5
The Dutch international toiled manfully all day long, but this was one game where he truly failed to impress. Lacked invention with his final ball, and his attempts to carve open the United backline were easily thwarted.
Stewart Downing (off 61') - 4
Terrible display from the England international, who once again left the Anfield faithful wondering why the club spent £20million on him in the summer.
Failed to have any sort of impact on the match, and was a liability when he decided to help out in defence. No surprise to see him hauled off just after the hour mark.
Luis Suarez - 8
Pre-match antics aside, Suarez once again proved to be Liverpool's biggest threat up front. Regularly found space and was always eager to get the better of Ferdinand with his dancing feet.
Pulled one back for the Reds when he showed good reactions to pounce on a poor touch by Ferdinand, although he failed to find a second which would have salvaged a point for his side.
Andy Carroll (on 61') - 6
Failed to impose himself in the opposition penalty box despite given plenty of time to make an impact.
Craig Bellamy (on 61') - 7
The Welshman must be wondering what he must do to earn a start. Despite regularly posing a threat whenever Dalglish fields him, Bellamy again had to start on the bench.
And he showed what he's capable off the moment he was brought on, providing plenty of width and pace down the left, and at least made Rafael accountable.
Charlie Adam (on 75') - N/A
Put in a couple of testing deliveries from set-pieces.