1. Arsenal give themselves a chance

Arsenal kept their slender hopes of finishing in the top four alive with a 2-0 victory over Manchester United at the Emirates on Sunday. Granit Xhaka and Danny Welbeck scored in a three-minute spell to end United's 25-game unbeaten Premier League run. Though Arsene Wenger's side must still rely on Liverpool and Manchester City dropping points, the 0-0 draw for Jurgen Klopp's side against Southampton at Anfield has offered the Gunners a remote chance of securing their 20th consecutive season of Champions League football.

Meanwhile, Jose Mourinho's side can all but give up any ambition of qualifying for Europe's premier competition through the league. Their best hope is to win the Europa League. They face Celta Vigo in the second leg of the semifinal at Old Trafford on Thursday holding a 1-0 lead; surely Mourinho's interest in the rest of the domestic season will be limited.

The United manager's thoughts were clearly on the Europa League based on Sunday's teamsheet. He made eight changes from the side that beat Celta and he set his team up to stifle Arsenal while looking for Anthony Martial on the break. It worked in a tight first half but nine minutes into the second half, Arsenal got a slice of luck that separated the sides.

United were having their best spell of possession at the beginning of the second half when Arsenal broke the deadlock in the most unlikely manner. Xhaka, for so long seen as the symbol of Wenger's poor judgement and the failure of Arsenal's transfer policy, took a speculative shot from 30 yards. It looked the sort of effort that David De Gea would scoop up with ease until the ball hit Ander Herrera on the back and looped into the net. No goalkeeper could have done anything about it. Mourinho will be unhappy with Herrera, who turned away from the shot and ducked, for his part in the goal.

Within three minutes, Arsenal had doubled the lead. Alex Oxlade-Chamberlain sent in a looping cross that Chris Smalling seemingly thought he could clear but the United defender jumped under the ball instead. Behind him, lurking, was Welbeck, who headed it expertly in off the bar. United's long unbeaten run was over.

Mourinho brought on Jesse Lingard and Marcus Rashford for Henrikh Mkhitaryan and Herrera but United were unable to trouble Arsenal and Wenger finally got his first league win over nemesis Mourinho.

Danny Welbeck celebrates after doubling Arsenal's lead. Richard Heathcote/Getty Images

2. United again misfire at top opposition

United's record away to the other clubs in the top six of the Premier League this season is appalling. They were routed 4-0 by Chelsea and drew 0-0 with Liverpool and Manchester City. They have not even scored against their rivals. Before the Emirates visit this weekend, Mourinho would have defended the record. He took a point from both the Etihad and Anfield but the lack of ambition in those performances was startling.

It was a similar situation against Arsenal. He made eight changes but it was still an experienced and talented XI. The only real surprise was the inclusion of Tuanzebe. The 19-year-old was given his debut at right-back and showed no nerves and had a good game.

At first it looked like another draw was on the cards and there was even a chance that United could nick the advantage. Mkhitaryan probed behind Oxlade-Chamberlain and set Martial free. Along with Mata, the pair enjoyed the freedom and space afforded them by Wenger's wing-back system. The problem is that neither United midfielder shows enough awareness tracking back.

Mata switched off during Arsenal's first attack and Alexis Sanchez was allowed to shoot from an narrow angle. Soon after, the two midfielders were tiring of getting up and down the field and settled in, staying back in their defensive positions. Martial was left isolated. Wayne Rooney dropped back into the midfield to help Michael Carrick and apart from a Rob Holding back-pass that gave Rooney a scoring opportunity, there were few chances for United. They looked toothless as they so often have this season.

IAN KINGTON/AFP/Getty Images

3. Ramsey helps Arsenal break United down

Until Xhaka's stroke of luck, it looked like Arsenal would struggle to unpick United.

Aaron Ramsey and Alexis Sanchez looked the likeliest to score. Ramsey caused United problems with his running from deep. The 26-year-old was driving down clever channels into the area while the static defensive line fixated on Sanchez instead. They were the sort of runs that Mesut Ozil might have been expected to take but once again the German was peripheral, sitting too deep and distributing the ball sideways rather than looking to pick a pass into the area.

Too often the home side were forcing the ball into the crowded middle of the field where United defenders could double up on Sanchez and Welbeck. But thankfully, Ramsey was the pick of the Arsenal side. His intelligence and touch made him stand out and on this form, he may yet be able to drag Wenger's team into the top four.

When they did get chances, De Gea showed his quality. Ramsey and Oxlade-Chamberlain must have thought they had broken the deadlock in the first half but the goalkeeper was equal to their efforts.

De Gea's brilliance is about more than stopping shots. The United goalkeeper has never really been phased by the various centre-back combinations deployed in front of him. At the Emirates it was Phil Jones and Smalling. De Gea organised them, warning them of any unseen danger and ensuring that Mourinho's defensive cordon held under extreme Arsenal pressure. But not even a goalkeeper as good a De Gea can cope with such a deflection for Arsenal's opening goal.