The Red Devils carried out a smash and grab job on a gutted home side and edged themselves closer to the first title in three years.
But Rafael Benitez's men can count themselves unfortunate to come away from the game with nothing after being more than a match for their opponents.
Liverpool started brightly and showed their intent to win the game early on as centre-back Daniel Agger hit a rocket from 35 yards which flew just over the bar.
Manchester United were always dangerous though, with Cristiano Ronaldo posing a constant threat to the home side's defence.
The Portuguese winger should have done better after great link-up play between himself and on-loan striker Henrik Larsson.
Ronaldo laid the ball to Larsson, who returned the favour with the cheekiest of flicks, but the twinkle-toed winger hit his shot way over the bar.
Despite United's obvious class it was Liverpool who came the closest to breaking the deadlock.
Dirk Kuyt was hauled down by Nemanja Vidic just outside the box and John Arne Riise's resulting free-kick was inches wide of the far post.
Title hopefuls United were always a threat on the break and would have been ahead but for some fantastic defending from Jamie Carragher.
Ronaldo skipped past Agger, but with seemingly a free shot at goal, the rock-solid Carragher threw himself in front of the shot before it could trouble Jose Reina.
The ball then rebounded to Larsson, whose through ball found Wayne Rooney through on goal, but Carragher produced a top-notch tackle to deny him getting his shot off.
Despite an action-packed first half the teams went in at the break all-square.
Liverpool began the second half similarly to the first and could have taken the lead twice in the opening minutes.
First a cross from the right fell to skipper Steven Gerrard, but the captain sliced his shot well over the bar.
Craig Bellamy was then denied a goal after a smart save from Edwin Van der Sar.
Bellamy then had the ball in the net after tapping home from the scramble in the box, but the linesman flag kept the scores level.
United also put the ball in the net but Rooney's cheeky backheel finish was ruled out for offside and the England striker picked up an injury after 74 minutes and had to be taken off.
Substitute Peter Crouch had a fantastic chance to win the game for Liverpool in the dying minutes, but his shot was brilliantly saved by the United keeper.
In the end it was the visitors who stole the three points after an 90th minute Ryan Giggs free-kick was spilled by Reina.
Substitute O'Shea reacted quickest and was there to whack the ball into the roof of the Liverpool net from point-blank range.
There was one unsavoury moment in the match when United's Paul Scholes was sent off four minutes from time for aiming a punch at Xabi Alonso after a midfield tussle.