The Gunners welcomed William Saliba back to their line-up after a World Cup break which deprived them of the injured Gabriel Jesus.
The Brazilian’s replacement, Eddie Nketiah, teed up Bukayo Saka for an early opener but the offside flag went up as a VAR check confirmed the slightest of touches from the winger to an offside Nketiah in the build-up.
In response, Arsenal piled on the pressure but lacked a cutting edge inside the box amid Jesus’ absence.
Martin Odegaard thought he had cracked the Hammers’ code in first-half stoppage time when a shot clattered into Aaron Cresswell, prompting Michael Oliver to point to the spot again.
However, VAR quickly intervened to send the referee to the screen and overturn his call, the ball having clearly hit the West Ham man’s head.
Arsenal’s cute, crafty approach continued after the break yet had absolutely nothing to do with their leveller as a scuffed Odegaard shot fell kindly for Bukayo Saka – usefully kept onside by Vladimir Coufal – to roll home.
Only five minutes later and still before the hour break, Gabriel Martinelli fired the hosts in front. The Brazilian’s cheeky near-post effort caught out Lukasz Fabianski and the quickfire turnaround was complete.
Nketiah made the points safe on 68 minutes, expertly rolling his marker and firing a low shot home.