What was supposed to be the first of five daunting, season-defining fixtures for Manchester United turned out to be nothing of the sort.
This trial of strength between Lancashire's two major football tribes was ruined as a contest from the moment, only four minutes into the game, when referee Mike Riley sent off Sami Hyypia, the Liverpool captain, for pulling down Ruud van Nistelrooy in the penalty area.
Van Nistelrooy duly despatched the penalty kick and effectively put United back on top of the Premiership for an hour or two. Liverpool, who are built to defend and counter-attack at the best of times, coped admirably with 10 men until the 65th minute, when Riley awarded United a second penalty. Van Nistelrooy converted that one as well and from then on it was just a question of how many goals they would score.
There were two more, from Ryan Giggs and Ole Gunnar Solskjaer, as United found some fluency and polished their attacking moves in preparation for a much sterner test, the first leg of their Champions League quarter-final against Real Madrid at the Bernabeu on Tuesday.
The four goals made this United's biggest victory over Liverpool for 50 years, completed the double over their bitter rivals and provided ample consolation for losing the Worthington Cup final to them last month.
Some, perhaps, may raise an eyebrow at the fact that yesterday's two penalties were the fifth and sixth Riley has awarded United at Old Trafford this season.
However, the Leeds official had little option in either case. The only criticism one could level at him is that the second decision looked harsher than the first, because the law says the player who concedes a penalty as the last defender, as Hyypia was, must go.
The trouble, as former Liverpool idol Ian St John pointed out on television, is that not all referees stick to the letter of that particular law. One example offered was the recent decision by Graham Poll to content himself with awarding a penalty against Tottenham's Gary Doherty for bringing down Bolton's Youri Djorkaeff in circumstances very similar to yesterday's.
But Liverpool manager Gerard Houllier had few complaints afterwards. Having admitted that Hyypia's challenge on Van Nistelrooy had looked a blatant penalty from the dug-out, he said the television replay had made it seem more like a just a tangle between the two players.
"The referee took his decision and we have to live with that," the Frenchman added, "but I just think he could have avoided sending Sami off."
Forced on to the back foot so early in the game, Liverpool took off striker Milan Baros, their replacement for the injured Michael Owen, and sent on utility player Igor Biscan to operate alongside Djimi Traore in a makeshift central defence. They and the other eight outfield players worked hard enough to retain some hope of a draw until Biscan conceded the second penalty midway through the second half.
"You always want to kill off the game, and that did it," said United manager Sir Alex Ferguson. "In the second half we played without running. We just passed the ball and saved our energy that way. That may help us on Tuesday night.
"If you were asked what you'd rather have, two League victories over Liverpool or the League Cup, what would your answer be?"
Liverpool's attempt to win this match, and improve their chances of finishing in a Champions League place, was in trouble from that early moment when Paul Scholes threaded a short pass through to Van Nistelrooy and Hyypia clearly brought down the Dutchman as they wrestled for control of the ball.
United ought to have had a second goal 10 minutes later, but Riley wrongly disallowed Mikael Silvestre's scoring shot for a legitimate aerial challenge on Jerzy Dudek by Rio Ferdinand and Wes Brown.
Dudek had to make a diving save from Silvestre and Traore cleared Giggs's follow-up shot off the line but Liverpool were relatively untroubled until the 57th minute, when a Giggs volley from 25 yards had Dudek leaping to turn the ball for a corner. Eight minutes after that, Biscan crashed into Scholes as the defender tried to clear a pass by Roy Keane and Van Nistelrooy's ninth goal from the penalty spot this season made sure of revenge over the old enemy. With Liverpool's energy exhausted and their morale broken, United frolicked around the visitors' goal.
Giggs, coming in behind Van Nistelrooy who failed to make contact with a centre from David Beckham - said to be under the weather and used here only as a substitute - stabbed in his first League goal at Old Trafford for two years. Then, in the last minute, Solskjaer completed this comprehensive win, and Liverpool's embarrassment, by beating Dudek easily at his near post.
Man Utd: Barthez, Gary Neville, Ferdinand, Brown, Silvestre (O'Shea 66), Solskjaer, Keane, Phil Neville (Beckham 66), Giggs, Scholes (Butt 79), van Nistelrooy.
Subs Not Used: Ricardo, Forlan.
Goals: van Nistelrooy 5 pen, 65 pen, Giggs 78, Solskjaer 90.
Liverpool: Dudek, Carragher, Hyypia, Traore, Riise, Diouf (Smicer 71), Hamann, Gerrard, Murphy (Cheyrou 80), Heskey, Baros (Biscan 6).
Subs Not Used: Arphexad, Mellor.
Sent Off: Hyypia (4).
Booked: Diouf, Murphy, Gerrard.
Ref: M Riley (W Yorkshire).
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