Fernando Torres and substitute David Ngog left Manchester United reeling as Liverpool brilliantly halted their four-game losing streak.
Liverpool boss Rafael Benitez had said prior to the game that one win would change everything, and what a result his team delivered to ease the pressure on the Spaniard.
The champions were eventually beaten after a stunning performance of defiance that followed days of the worst crisis Liverpool have suffered in decades.
If the critics were to be believed, boss Benitez was for the chop, Liverpool were all washed up and facing financial ruin.
Well not after this cracking Barclays Premier League battle. Liverpool restored their pride with a victory over, for them, the best victims possible.
Torres forced his injured frame through the game and grabbed his ninth goal of the campaign midway through the second half to get Liverpool really firing.
Ngog hit the second in stoppage-time, with the match at boiling point. United had by that stage lost defender Nemanja Vidic to his third red card in successive matches against Liverpool.
Javier Mascherano saw red too, but it was Liverpool who inflicted the second league defeat of the season on United to restore faith among their worried fans.
As expected, Steven Gerrard missed the match with a groin problem, but Wayne Rooney recovered from a calf injury to play for the champions.
Liverpool had Torres and Glen Johnson back after both missed the Champions League defeat to Lyon on Tuesday, while United also had Ryan Giggs, Patrice Evra and Michael Carrick back in their starting line-up. Michael Owen, facing his former club, started on the bench and on his introduction received a punishing reception from the fans who once worshipped him.
United's supporters made the most of Liverpool's recent misfortune. Beach balls, Eric Cantona masks and insulting banners were smuggled into the away section.
The banner that hurt most, no doubt, was "You told us to come back when we'd won 18 titles...well, we're back".
Watching on were co-owners Tom Hicks and George Gillett, sitting side by side in the directors' box, but not in the exposed front row.
The atmosphere was electric, the noise deafening, as Liverpool set about trying to restore their battered reputation.
Evra was booked after two trips on Torres in as many minutes, and from the free-kick Fabio Aurelio sent in a curled effort that Edwin van der Sar clawed away. It went straight to Dirk Kuyt, whose follow-up was also saved by his Dutch countryman.
Then Lucas robbed Paul Scholes and gave Kuyt another chance, this one guided wide of the far post.
Rooney, who had seen one effort disallowed for offside, rose to met an Antonio Valencia cross, but his header was held low to his right by Jose Reina.
United had better possession and hit Liverpool with pace and slick movement, but Van der Sar was again needed to plunge to his right to keep out an Aurelio header from Yossi Benayoun's cross.
Then Dimitar Berbatov was booked for a trip on Lucas, with the game finely balanced as the half ended.
Kuyt should have scored early in the second period when he was played in by Johnson, but he chose to pass rather than blast an angled effort, and the chance was lost.
Then Benayoun's touch sent Torres away on the right, but his lack of genuine pace following his groin problem did not see him shake off Rio Ferdinand, and again the opening went begging.
It then needed a block from Johnson on the far post to keep out Rooney's header from Giggs' free-kick.
But Liverpool were growing in confidence and they grabbed the lead after 65 minutes. Benayoun's pass sent Torres beyond Ferdinand, onside only by inches.
The Spaniard was not going to be denied this time. He held off the England centre-back and lashed a shot into the roof of the net. The roof almost came off Anfield too.
Mascherano was booked for a foul on Evra before Anfield had its first sight of Owen in a United shirt as he came on for Berbatov and Nani replaced Scholes after 74 minutes.
Owen's arrival was greeted with jeers and chants of "Where were you in Istanbul?" as well as "Once a Manc, never a Red".
Vidic was booked for a foul on Torres, and then after 80 minutes Torres could run no more and Ngog took his place.
Valencia saw a cross-shot clip the Liverpool bar and Owen was searching for any inch of space. He almost had a chance when he chased a through-ball, only to be hauled down by his good friend Jamie Carragher. The Liverpool skipper was booked.
With just a minute of normal time left, Vidic pulled down Kuyt as the Dutchman raced into an empty half. Red followed a second yellow, and the Serbian was sent off for the third successive game against Liverpool.
Three minutes into added time Mascherano was also sent off for a challenge on Van der Sar, the Argentinian's second yellow-card offence.
Then came the killer blow to United. Liverpool broke from deep defence, Lucas delayed his pass to sent Ngog away on his own and the striker slid the second past Van der Sar. Anfield, and Benitez, could finally celebrate.