It took the Gunners 51 minutes to open the scoring on a day of high emotion at the Emirates as Nacho Monreal fired in his sixth goal of the season in all competitions.

Marko Arnautovic drew the Hammers level with a fine strike in the 64th minute but after a defensive error saw Aaron Ramsey put Arsenal back in front, a late Alexandre Lacazette brace made sure of the points.

Wenger made the surprise announcement on Friday morning that he will bring the curtain down on his Gunners tenure at the end of the season after almost 22 years in charge.

Arsenal did not put on a vintage display for their boss in the first half but they had the game's first real chance as Laurent Koscielny headed narrowly wide from Granit Xhaka's corner.

Arnautovic latched onto West Ham goalkeeper Joe Hart's punt forward before bursting into the box a few minutes later, only to be dispossessed by Shkodran Mustafi before he could get a shot away.

The Austrian went close again in the 15th minute as his fierce angled shot was beaten away by Gunners goalkeeper David Ospina after some shaky defending from the hosts.

Cheikhou Kouyate then headed onto the top of the bar as West Ham began to dominate.

Arsenal forward Danny Welbeck's 20-yard effort flashed wide of the post in the 25th minute before Xhaka saw his free-kick saved by Hart as Arsenal began to threaten.

There was bad news for the Gunners in the closing stages of the first half as influential midfielder Mohamed Elneny was carried off on a stretcher after a challenge with Mark Noble.

Arsenal started the second period brightly and broke the deadlock in the 51st minute as Monreal volleyed Xhaka's corner into the back of Hart's net from the middle of the area.

The hosts had the wind in their sails and poured forward in search of a second.

Alex Iwobi galloped down the right flank two minutes later but his deep cross could not find a red shirt.

After blazing over from close range in the 63rd minute, Arnautovic saw the net bulge a minute later as he rifled the ball into the far corner from the left side of the box.

With the game back in the balance, Hart produced a phenomenal save to prevent Welbeck from putting Arsenal back in front with a curling shot from the edge of the area in the 79th minute.

But it would be a defensive mix-up that saw Arsenal regain the lead in the 82nd minute as Declan Rice ducked out of a defensive header and Ramsey's cross-cum-shot sailed past a confused Hart.

And Lacazette made sure of the points late on as he followed up his deflected 85th-minute goal with a fine strike from the middle of the area in the 89th minute.