Arsene Wenger's Arsenal tear Louis van Gaal's strollers apart

To behold Louis van Gaal's version of it yesterday was to watch a team whose strange, stuttering, sideways, backwards style did not betray the perilous position they found themselves in. By seven minutes, United were two down and clinging on. By 20 minutes, Alexis Sanchez had scored the third and the game was over.

We waited in vain for United to spark into life. How often have a United side been dead and buried with three-quarters of the game left to play?

Chugged

They chugged along in second gear all afternoon, with the only real action going on around Anthony Martial, who did his growing reputation no harm in a team where much more famous names had the kind of game that will make Van Gaal, or his successor, wonder how long this can go on.

Van Gaal declared himself "surprised" at the reaction of his side and then checked himself.

"Amazed," he said, "maybe that's a better word. When you give a team like Arsenal so much space to play football, you know you shall lose. We have prepared ourselves in that way and to play more compact but not to lose our aggression. It was amazing for me and very disappointing."

This is not a Moyesian crisis by any means for United, who are still third in the table just behind Arsenal. United might take reassurance, after all, that they have been beaten just twice in the league. Yet this was the first top-four side from last season they have faced this time around and the truth is that Van Gaal's team crumbled early on.

They lost, the United manager said, in a way "you cannot lose when you are top of the league".

On the subject of Wayne Rooney, whose desperate first half epitomised United's frustrations, Van Gaal tied himself in knots.

"When I say it (talk about Rooney) in a positive way, it's maybe not good. When I say it in a negative way it is tomorrow's headlines that I'm not satisfied with the performance of Rooney. I talk about the team and Rooney is a very important part of the team."

It was a polite way of saying that if he could not say anything nice, it was best not to say anything at all. Rooney was not alone. A midfield missing Morgan Schneiderlin was demolished in the first half by the brilliant Sanchez, who, with two goals, was well supported by a tigerish Theo Walcott and Mesut Özil.

In truth, this could have been much worse for United, whose ponderous attempts to claw back a second-half goal, with Marouane Fellaini on at half-time, left them open at the back.

Özil, a first-half goalscorer, as well as substitutes Olivier Giroud and Alex Oxlade-Chamberlain, might have taken the score higher with chances as good as any United carved out. For once, Arsenal had seized the moment and they looked magnificent at times.

The home support roared the whistle for half-time. They roared it as emphatically as they had booed full-time against Olympiakos five days earlier.

This was what they pay the highest ticket prices in the Premier League to watch: fast, incisive football, with ruthless finishing good enough to slice open a team that one of their oldest rivals has spent a fortune building.

"I know that what you want is a strong response when you have a big disappointment," Arsène Wenger said. "We have to put it all in perspective and focus on what is important. The pressure on any disappointment is massive, it makes it a bit more difficult to deal with it and we did it well."

Without Schneiderlin, Bastian Schweinsteiger and Michael Carrick stood off Arsenal to the extent that the first two goals began in the home side's half with passes being exchanged at walking pace. They were through United and in for two goals in the space of a minute.

Sanchez's first, brilliantly flicked in at the near post from Özil's cross was a move that began deep in the Arsenal half. United won it back briefly but Memphis Depay then lost it and the next time they had the ball it was in their own net.

A minute later, a sequence of passes from Sanchez to Özil, on to Walcott and back to Özil made the chance for the German, who finished smoothly.

Broken

Two goals down in seven minutes, United already looked broken. Ashley Young, at left-back, slotted the ball into touch. Rooney's first major involvement was an immediate turnover of possession.

By the time Sanchez picked the ball up on the left with 19 minutes gone, United had run out of ideas for stopping him. The Chilean cut in on his right foot and had a bit of luck with one ricochet, but then things like that happen when a player is performing at his level.

He lashed a shot past David De Gea and you wondered whether this one might have to be stopped on humanitarian grounds. Arsenal should have had four by half-time, when Aaron Ramsey was played onside by Young at the back post from Sanchez's cross.

Otherwise this was an occasion when Arsenal punished their opponent at every opportunity.

United's best hope was Martial and his turn and shot on 44 minutes was beautifully executed, although Petr Cech had closed the angle as the teenager swivelled and got a foot in front of the ball.

Matteo Darmian and Depay both went off at half-time. Arsenal should have scored more. Rooney went off at the end delivering Carrick what looked like an anguished complaint about the state of United, and both will know that they too could have done much better.