Goals from Mesut Ozil, Theo Walcott and sub Olivier Giroud gave Arsenal a much-needed 3-0 win over West Ham on Wednesday night in the Premier League.
Ozil gave Arsenal the lead on 58 minutes with a left-footed shot from the edge of the area, though Darren Randolph should have done better in the West Ham goal.
It was 2-0 just 10 minutes later through Walcott, who struck home from 10 yards after Ozil's centre from a fine Arsenal move.
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The third came seven minutes from time through Giroud, who curled a fine effort into the corner from 15 yards just nine minutes after coming on.
The result means Arsenal are back in the top five on goal difference, while West Ham are five points off the drop zone.
Arsenal were forced to start third-choice goalkeeper Emiliano Martinez due to injuries to David Ospina and Petr Cech, and also introduced Gabriel and Mohamed Elneny.
West Ham had the better of the early chances, as Manuel Lanzini struck just over from a free-kick, before Mark Noble missed the far post with a low effort from inside the area.
Arsenal had a strong penalty appeal turned down by Martin Atkinson after Theo Walcott was hauled down by Arthur Masuaku.
The hosts nearly went into the half 1-0 up, but both Hector Bellerin and Elneny saw their efforts from close range desperately blocked.
Arsenal upped the tempo in the second half, and got their opener through Ozil's tame effort from the edge of the box, which Randolph parried into the net.
Randloph kept West Ham in the game for a few more minutes at least with a good low save from Danny Welbeck's poked effort in the area, but he couldn't keep out Walcott on 68 minutes.
Alexis Sanchez's backheel found Ozil down the left channel, and his centre was met first time by Walcott, who drilled the ball into the bottom left corner.
Bellerin slid the ball just wide from Ozil's delightful ball over the top of the defence, before Giroud made it 3-0 with a superb curling effort from inside the box after being found by fellow substitute Alex Oxlade-Chamberlain.
Arsenal were denied a blatant penalty in stoppage time after Sam Byram hacked down Nacho Monreal, but it mattered not as Arsene Wenger's side moved back into the hunt for the top four.
Arsenal: Martinez (6), Bellerin (6), Mustafi (6), Gabriel (6), Monreal (6), Elneny (7), Xhaka (7), Walcott (7), Ozil (7), Alexis (7), Welbeck (6)
Subs: Oxlade-Chamberlain (7), Giroud (7), Ramsey (NA)
West Ham: Randolph (5), Byram (4), Fonte (5), Collins (5), Masuaku (5), Noble (6), Kouyate (5), Ayew (5), Lanzini (5), Antonio (5), Carroll (5).
Subs: Snodgrass (5), Sakho (NA)
Man of the match: Mesut Ozil