Mikel Arteta's side ran riot in the first half at the London Stadium, scoring five times to move six points behind leaders Liverpool, who host spluttering champions Manchester City on Sunday.

Gabriel Magalhaes opened the floodgates with an early goal before Leandro Trossard doubled Arsenal's lead.

Martin Odegaard's penalty was followed by Kai Havertz's ninth goal this season.

Aaron Wan-Bissaka and Emerson struck in quick succession for West Ham, but Bukayo Saka's penalty capped a virtuoso performance from the Arsenal forward.

The Gunners' title hopes were badly damaged by a run of four league games without a win prior to beating Nottingham Forest last weekend.

Arteta admitted this week that Arsenal must be almost perfect to catch Liverpool.

And, following their 5-1 thrashing of Sporting Lisbon in the Champions League on Tuesday, this was further evidence that, while Arteta's team might not be perfect yet, they are undoubtedly back on track.

Arsenal's first top-flight away win since September was a timely reminder that the team who pushed City to the brink in the title race last term should not be written off with over half the season left.

Chasing a first title since 2004, Arsenal have been revitalised by the return of captain Martin Odegaard, who was sidelined for 12 matches in all competitions with an ankle injury.

Since the Norway midfielder was restored to the starting line-up, Arsenal have gone unbeaten in four successive games, with Manchester United due to visit the Emirates Stadium on Wednesday.

West Ham boss Julen Lopetegui had lifted some of the mounting pressure on him with Monday's win at Newcastle.

But Arteta, who hails from the same Basque region as his close friend Lopetegui, showed no mercy as Arsenal seized control in an astonishing first half.

- Rampant Arsenal -

Arsenal won 6-0 on their previous visit to the London Stadium in February and once again they were unstoppable in Stratford.

Not for the first time this term, it was set-piece coach Nicolas Jover who masterminded Arsenal's opener.

Saka curled in a corner and Gabriel capitalised on Jover's clever routine as he found space to glance his stooping header into the far corner from six yards.

The visitors struck again in the 27th minute, with Saka and Odegaard linking superbly in midfield before the former's pass was slotted home by Trossard from close range.

Rampant Arsenal were carving open the hosts' defence at will and it was no surprise when they netted again seven minutes later.

Lucas Paqueta tripped Saka in the area and Odegaard stepped up to stroke in the spot-kick for his first goal since April.

With West Ham in disarray and shell-shocked fans already heading to the exits, Havertz piled on the misery in the 36th minute.

Trossard's raking pass sent Havertz clean through as West Ham defender Max Kilman comically slipped, giving the German time and space to shoot low beyond Lukasz Fabianski.

Wan-Bissaka punctured Arsenal's momentum in the 38th minute, breaking into the area and drilling past David Raya from Carlos Soler's pass.

Two minutes later, Arteta wore a furious expression after West Ham left-back Emerson bent a fine free-kick into the top corner from 25 yards.

But Arsenal's unexpected wobble was a false dawn for West Ham.

Deep into first half stoppage-time, Fabianski accidently punched Gabriel in the head as they challenged for a corner, conceding a penalty that Saka squeezed past the Pole's weak attempted save.

The combined seven goals equalled the record for the most in the first half of a Premier League game.

After Gabriel was forced off at the interval, Arteta's only concern in the second half was avoiding any more injuries as Saka, Odegaard and Trossard all played on despite being on the receiving end of crunching tackles.