London - Mikel Arteta got everything he asked for in his first win as Arsenal manager with a rampant first 45 minutes from the Gunners earning a 2-0 victory over Manchester United at the Emirates.
Nicolas Pepe and Sokratis Papastathopoulos scored the goals to secure just a second win in 16 games.
Arsenal started the game three times as many points off the top four as the relegation zone, but a first home win in 87 days hauls Arteta's men up to 10th and within four points of United in fifth.
"I am very pleased with the performance, I'm even more pleased with the result," said Arteta after his third game in charge. "Everything I wanted to see on the pitch, I saw tonight."
There were signs of encouragement for Arsenal in Arteta's home debut against Chelsea on Sunday when only a late collapse saw a 1-0 lead turn into a 2-1 defeat.
However, this time the hosts saw the game through as a dismal United performance raised fresh questions over their chances of finishing in the top four.
"At the moment we are suffering to maintain that level of intensity of the first halves," added Arteta.
"That will come, but as well I really liked the resilience they showed. I liked to see them suffer together."
Ole Gunnar Solskjaer's men were again shorn of Paul Pogba, who faces another month out after an operation on a troublesome ankle injury that has kept him out for the majority of the season.
Pogba's absence is still evident in United's inability to create when denied the chance to counter-attack and they failed to recover after falling behind early on.
"After they scored the first goal, it seemed like they got loads of energy," said Solskjaer.
"They were the better team. They were aggressive, they regained the ball and it was hard to get the ball off them."
For the first time Arsenal started with all of Pepe, Pierre-Emerick Aubameyang, Alexandre Lacazette and Mesut Ozil together in attack and Arteta's bold choice paid dividends eight minutes in.
Pepe scored just his second Premier League goal from open play since a 72 million move from Lille when he swept home Sead Kolasinac's cross at the back post.
The Ivorian was suddenly brimming with confidence as he twisted and turned Luke Shaw before crossing for Aubameyang to volley just over.
Lacazette then rolled Harry Maguire easily in a night to forget for the world's most expensive defender before pulling his shot across goal.
David de Gea is another of United's more experienced stars suffering an alarming dip in form and a poor clearance from the Spaniard offered another sight of goal to Pepe, whose long-range strike came back off the post.
Arsenal's first half dominance was rewarded with a second goal before the half-time interval as De Gea could only palm Lacazette's header from a corner back into the danger area and Sokratis pounced to fire into the roof of the net.
As the hosts' energy levels dipped from a frantic first 45 minutes, United were allowed to dictate the game but did not have the guile to make their possession count.
Andreas Pereira had the best chance to give United a lifeline but fired into the side-netting from Nemanja Matic's clever reverse pass.
"We have to be honest and admit physically we are not ready, but you have to show heart and this team is ready to change a lot of things," said Arsenal defender David Luiz.