Arsenal substitute Eddie Nketiah struck late to give Arsenal a 2-1 victory over a stubborn West Ham United.
Alexandre Lacazette gave Arsenal the lead in the 25th minute, heading in powerfully from Pierre-Emerick Aubameyang's cross.
West Ham levelled on the stroke of half-time after Ryan Fredericks' low cross was tucked in by Michail Antonio.
The Hammers striker then headed against the crossbar as the dominant visitors pushed for a second goal.
But Nketiah tapped in with five minutes remaining following neat build-up play by Bukayo Saka and Dani Ceballos to secure a hard-fought win, maintaining their 100 per cent start to the campaign.
Budweiser King of the Match Pierre-Emerick Aubameyang
See: Arsenal report | West Ham report
Next fixtures
Arsenal: 28 Sep v Liverpool (A)
West Ham: 27 Sep v Wolves (H)