Fighting in the tunnel at half-time is not really to be recommended as a stimulant, but it seemed to work like smelling salts on Manchester United, who took advantage of the quite unnecessary prolongment of the Luis Suárez affair to return to the top of the table through two goals in two minutes from Wayne Rooney.

The renewed feud between Patrice Evra and Suárez apart, the first half of this game was even more soporific than the original one at Anfield. In October, before all the trouble started, Kenny Dalglish described that game as "sterile", while Sir Alex Ferguson confessed it never really got going. This encounter was failing to live up to its billing by a similar distance until a couple of incidents at the end of the first 45 minutes woke everyone up.

First Suárez complained bitterly about a tackle by Rio Ferdinand that definitely denied him a clear goalscoring opportunity, though it did not strike many other people as illegal. The Uruguayan was still furious as the half-time whistle went and kicked the ball away in disgust; then an exchange of views as the players left the pitch turned into a fracas requiring police intervention in the tunnel area.

The Old Trafford crowd did not see any of that, but they could hardly help noticing the difference when the second half started. Rooney plundered two goals in two minutes with almost insouciant ease and could have had a hat-trick before the hour came up, as the defensive solidity Liverpool had shown in the first half evaporated in front of the Stretford End.

The first goal came from a corner, with questions to be asked of the visitors' marking after Michael Carrick gained the slightest of touches on Ryan Giggs's cross to leave Rooney a close-range opportunity he was never going to miss. Before Liverpool had properly recovered their composure, Jay Spearing gave the ball away to Antonio Valencia in a dangerous area, leaving the winger with the simple task of playing Rooney clear through the middle to strike a low shot under Pepe Reina.

The chance Rooney missed 10 minutes later was perhaps even easier. Again the impressive Valencia was involved and, when Paul Scholes stepped over his cross it gave Rooney another clear sight of goal from close in, yet his shot missed the target. "I probably should have had a hat-trick, but I snatched at the last one, to be honest," Rooney said. "The first goal was always going to be the important one, though. Once we got in front, Liverpool didn't cause us too many problems until right at the end."

Dalglish brought on Andy Carroll, Craig Bellamy and eventually Charlie Adam as Liverpool tried to find a way back into the game, though the substitutes did little except prompt some new chants of derision from the home crowd. When Liverpool did pull a goal back, to make the last 10 minutes more interesting, it was through the player who had been centre of attention all afternoon, Suárez popping up in the right place when Jonny Evans, then Rio Ferdinand, failed to cut out a free-kick, to hook the ball past David de Gea.

The last 10 minutes were not as interesting as all that, though, just as he did at Chelsea last week, De Gea produced a save in stoppage time to make sure United got the result they wanted, palming over a long shot from Glen Johnson that was about to dip under his bar.

The United goalkeeper had not had a great deal to do in a generally subdued first half, when what few chances there were went to the home side. Reina did well to save a shot from Rafael da Silva that he could only have seen late, then got lucky when Scholes ghosted in to meet a Giggs cross as if the past 10 years had never happened, never mind his supposed retirement. But he put his header straight at the keeper's gloves.

United's two veterans were linking well and controlling the game in a manner that must have worried Liverpool supporters, especially as the visitors had five men in midfield, but the interval arrived after one more scare for their defence, when Giggs's pass put Danny Welbeck behind the back line, but the striker opted to cross instead of going for goal.

"We made it difficult for ourselves by conceding two goals so quickly, but at least we got back into the game," Dalglish said. "Overall, you would have to say United were the better side, but it was only that five-minute spell that cost us."

The Liverpool manager said on television he was unaware of Suárez's refusal to shake Evra's hand, which, in itself, is revealing of the way in which the Merseyside club have failed to monitor, let alone manage, this awkward situation. Ferguson said it was a terrible way to start the game and had created a terrible atmosphere, which was not strictly true, unless he was referring merely to the ill-feeling between the players that simmered until boiling over at half-time. Looking exactly like a man who has had enough of patience and politeness, and decided the time had come to vent his true feelings, Ferguson went on to say a lot more about the behaviour of Suárez and Liverpool, the upshot of which was that Dalglish decided to give the post-match press room a miss.

There was no official explanation for the no-show, though presumably he would have been uncomfortable when presented with his rival manager's comments. This was perhaps the first occasion in five months when Liverpool have been silent on the subject. If only some of their earlier responses had been as eloquent, the matter might never have been allowed to overshadow their season.