Swansea 0 – 3 Arsenal
Giroud 49′ Koscielny 68′ Campbell 73′
Joel Campbell scored on his first Arsenal league start to help the Gunners defeat Swansea City and earn a fifth straight Premier League win.
Olivier Giroud headed the visitors into the lead after half-time, his fourth goal in five club appearances.
Laurent Koscielny doubled the lead after former Gunners keeper Łukasz Fabianski dropped the ball before Campbell lashed home the third.
Bafetimbi Gomis wasted a great chance for Swansea from close range.
Swansea striker Bafetimbi Gomis missed two opportunities to give the hosts the lead, as Hector Bellerin raced back to win the ball off the French international from a one-on-one opportunity with Petr Cech, before the Arsenal keeper kept out a header from the former Lyon man.
In other dramatic developments: Arsenal twice came close to taking the lead before half time, as Olivier Giroud curled an effort over the bar, before Swansea keeper Lukasz Fabianski denied Campbell. After the break the visitors took control of proceedings, and scored the opener on 49 minutes as Giroud rose highest at a Mesut Ozil corner to head past Fabianski.
Swansea almost pegged their opponents back immediately, as Gylfi Sigurdsson forced a save from Cech, before the Czech stopper tipped away a Ki Sung-yeung flick-on from a corner. Arsenal doubled their lead on 68 minutes, as former Gunners keeper Fabianski dropped the ball under pressure from Giroud, before Laurent Koscielny reacted quickest to tap into an empty goal.
The visitors added a third goal just five minutes later, as Mesut Ozil set up Campbell in the penalty area for his first Arsenal goal. Ashley Williams came close to finding a consolation goal late on, as the centre-back advanced towards goal before testing Cech at the near post.