Rafael Benitez might end up having the last laugh after all as his Liverpool side hauled themselves back into the title fight with a decisive crushing of 10-man Manchester United at Old Trafford.

The Merseyside giants battled back from a goal down to defeat the Premier League leaders in clinical fashion, Fernando Torres and Steven Gerrard turning the match on its head before the break, with Fabio Aurelio and Andrea Dossena easing Liverpool well clear before the end.

In contrast, it was an day to forget for Nemanja Vidic, who gifted Torres the equaliser before being sent off against Liverpool for second time this season as Benitez's side reduced United's lead at the top to four points, albeit having played a game more.

It represented Liverpool's biggest win at United since 1936 and could yet trigger an amazing championship revival.

Liverpool were the ones who needed the win and there appeared an extra sharpness about them from the start, especially Torres who gave the Red Devils defence a torrid time.

Once Jamie Carragher had recovered his composure after being unsettled by a late switch to right-back because of Alvaro Arbeloa's late withdrawal, they had the edge in vital areas, the hosts no better than their nervy first-half display against Inter Milan in midweek.

Indeed, it was a surprise when United went ahead.

Pepe Reina read Carlos Tevez's through ball for Park Ji-sung well enough but came out too quickly for his own good. When the South Korean nicked the ball away, the Liverpool keeper could not stop.

And though Reina pleaded for leniency, referee Alan Wiley correctly pointed to the spot.

Ronaldo is not the type of player to waste such opportunities and duly dispatched his 17th goal of the season.

Had Sir Alex Ferguson's men been able to hold their advantage for a decent length of time, the visitors might have panicked. But five minutes later Liverpool were level thanks to a rare mistake from Nemanja Vidic.

The Serbian has been virtually foot perfect this season, so much so that he is favourite to win the PFA player of the year award.

But first Vidic let Martin Skrtel's long punt forward bounce when he could have headed it back into the Liverpool half quite easily. Then, he failed to deal with the loose ball, allowing Torres to nip in and streak clear, beating Edwin van der Sar with clinical efficiency.

Conceding one goal was amazing enough for the Red Devils, yet before half-time Liverpool had scored again.

Hull were the last team to score more than once against United in Premier League combat - and that was four-and-a-half months ago.

But when Torres tried to send Gerrard racing into the box and Patrice Evra mis-timed his tackle, the Liverpool skipper found he converted his penalty with the same confidence Ronaldo had shown earlier.

Gerrard's glee was obvious. And Liverpool's lead was fully deserved, condemning Ferguson to his first interval rallying call in league combat at Old Trafford all season.

The Scot injected a greater sense of urgency into his team, even if there was no improvement in their retention of the ball.

Carrick in particular was having a pretty bad day, twice putting his side in danger with wayward passes.

United at least managed to generate some momentum, with Tevez almost getting on the end of a Wayne Rooney knock-back and then rolling a shot on the turn just wide.

Having expressed his 'hatred' of Liverpool earlier in the week, the last thing Rooney wanted was to suffer an immediate defeat and a chance for Gerrard - a long-time friend - to gloat.

Yet as time ticked by, that was the fate Rooney was condemned to, especially as Ferguson waited until less than 20 minutes remained before he made the introductions of Dimitar Berbatov, Paul Scholes and Ryan Giggs.

It is the kind of strength Benitez does not have and one of the major reasons why Liverpool have found themselves on the wrong end of a 14-point swing in fortunes since United returned from their Club World Cup campaign in Japan just before Christmas.

What Liverpool have managed to do this season is beat Chelsea and United, against both of whom they have now registered 'doubles'.

Any hope United had, evaporated within a minute of Ferguson's spectacular triple substitution as another woeful first touch, again from Vidic, left the Serbian little alternative other than to haul down Gerrard.

For the second successive game against Liverpool, it brought Vidic a red card and he was still making his way down the tunnel when Aurelio curled home a superb free-kick.

And Liverpool were not finished as Andrea Dossena lobbed Van der Sar to complete a memorable win, whose significance remains unknown.

Teams:

Man Utd Van der Sar, O'Shea, Ferdinand, Vidic, Evra, Ronaldo, Carrick (Giggs 74), Anderson (Scholes 73), Park (Berbatov 74), Rooney, Tevez.

Subs Not Used: Foster, Nani, Evans, Fletcher.

Sent Off: Vidic (76).

Booked: Ferdinand, Van der Sar.

Goals: Ronaldo 23 pen.

Liverpool Reina, Carragher, Skrtel, Hyypia, Aurelio, Mascherano, Lucas, Kuyt, Gerrard (El Zhar 90), Riera (Dossena 67), Torres (Babel 81).

Subs Not Used: Cavalieri, Insua, Ngog, Arbeloa.

Booked: Carragher, Mascherano, Skrtel.

Goals: Torres 28, Gerrard 44 pen, Aurelio 77, Dossena 90.

Att: 75,569

Ref: Alan Wiley (Staffordshire).