Louis van Gaal was “amazed” by Manchester United’s display as Arsenal got back to winning ways in emphatic style with a 3-0 home victory.

An air of positivity had been building around Old Trafford after a run of four straight wins in all competitions.

United began the weekend atop the Barclays Premier League standings, but have now been usurped by Manchester City and Arsenal after an embarrassing defeat at the Emirates Stadium.

Exceptional Alexis Sanchez efforts either side of a fine Mesut Ozil strike meant the match was over inside 19 minutes, leaving Van Gaal as perplexed as he was angry.

“I didn’t expect that,” he said. “I was surprised – not performing our game plan, not the will to win. I didn’t see that. We were top of the league so I was surprised – amazed, maybe that is a better word.

“When you give a team like Arsenal so much space to play football, then you know that you shall lose. And we have prepared ourselves also in that way, to play more contact but don’t lose your aggression. It was amazing for me and I am very disappointed.

Van Gaal bemoaned United’s lack of intensity, aggression and pressing afterwards. “I put the question already at half-time and also after the match because normally I say the things how I see it in the game. We have lost, we have lost in a way that you cannot lose when you are top of the bill or top of the league. You cannot start like we have started and they know that.”

As for Wenger, who had bristled this week when asked about the decision to leave Petr Cech out of the starting line-up in Tuesday’s 3-2 defeat by Olympiacos, the Arsenal manager said: “I’ve been at the club for 19 years and I know what you want is a strong response in a big game when you have a big disappointment,” he said. “To win in a big game is always a statement. We are in it, we are two points off the league leaders, Manchester City, so I hope that result today will give us belief to fight for it.”

Tottenham manager Mauricio Pochettino, meanwhile, hailed the dead-ball brilliance of Christian Eriksen after the Dane’s free-kick double in the 2-2 draw at Swansea.

Eriksen rescued a Barclays Premier League point for Spurs after they had twice fallen behind at the Liberty Stadium, the second time when England striker Harry Kane volleyed Jonjo Shelvey’s corner into his own net.

The goals were the Denmark midfielder’s first of the season after an injury-hit start to the campaign, but the 23-year-old has underlined his reputation as one of the best free-kick exponents in English football.

“He is one of the best at dead-ball situations, it is hard to say he is the best but he is one of the best,” Pochettino said. “He has natural ability but he also spends time working on it. They were great free-kicks, he has quality when he shoots and delivers a free-kick.”

Swansea have now gone four games without a league win but manager Garry Monk felt it was a much improved performance from last weekend’s 3-1 defeat at Southampton.

“We talked all week about getting back to our level, and you could see the passion and the desire we had to win the game was massive,” said Monk.

“Without the two free-kicks, I think we would have won the game and we certainly didn’t deserve to lose it.”