Santi Cazorla’s stoppage-time penalty gave Arsenal a dramatic victory over a determined Southampton side.
Saints took the lead when Petr Cech tipped a Dusan Tadic free-kick onto the underside of the bar but the ball bounced in off the Gunners keeper.
Laurent Koscielny equalised with a spectacular overhead kick after Cazorla’s corner was not cleared.
The hosts toiled in attack but Cazorla won it for them after Jose Fonte was judged to have fouled Olivier Giroud.
The result was harsh on Southampton, who were well-organised at the back and dangerous when they broke forward.
Saints remain winless under new manager Claude Puel, while Arsenal are five points behind Premier League leaders Manchester City, who beat Manchester United earlier on Saturday.