Arsenal recorded their first Premier League win under new manager Unai Emery after Issa Diop’s own goal and Danny Welbeck’s late strike saw West Ham fall to their third straight defeat.
The Gunners, beaten by Manchester City and Chelsea in their first two outings, bounced back through a Nacho Monreal strike, an Issa Diop own goal and a Danny Welbeck tap-in after Marko Arnautovic had given United a surprise lead.
The 21-year-old Diop became the eighth player to score an own goal on his English topflight debut and the first Hammer to do so in the competition.
West Ham captain Marko Arnautovic put the visitors in front on 25 minutes, exchanging passes with the impressive Felipe Anderson before slotting low past Petr Cech.
Nacho Monreal equalised five minutes later, firing into an unguarded net after Bellerin’s cross deflected into the defender’s path off Alex Iwobi.
West Ham meanwhile remain pointless and rooted to the bottom of the table.
Results from Saturday’s EPL matches
- Wolves 1 Man City 1
- Arsenal 3 West Ham 1
- Bournemouth 2 Everton 2
- Huddersfield 0 Cardiff 0
- Southampton 1 Leicester 2
- Liverpool 1 Brighton 0