Henrikh Mkhitaryan made his Arsenal debut on Tuesday, but the Gunners lost in south Wales to Swansea City, as Sam Clucas scored twice in the 3-1 upset.
Nacho Monreal gave the Gunners a short-lived lead in the first half, but Clucas equalised less than 60 seconds later.
A blunder from Petr Cech gave Jordan Ayew his goal on a platter after the break before Clucas scored again to secure the win.
Here's a look at the teams, via James Olley of theLondon Evening Standard:
The Welsh hosts came out firing, threatening Arsenal early.