Olivier Giroud netted his first Barclays Premier League goal as Arsenal came from behind to beat West Ham 3-1 at Upton Park.
The Gunners had seen their unbeaten start to the new season ended by a 2-1 home defeat against leaders Chelsea last weekend, but Arsene Wenger's men, who beat Olympiacos in the Champions League on Wednesday night, showed great character to recover from conceding an early goal to Mohamed Diame.
France striker Giroud, a £12million summer signing from Montpellier, netted from close range just ahead of half-time, with substitute Theo Walcott slotting home another on the break before industrious Spaniard Santi Cazorla struck a superb 25-yard effort.
Arsenal started brightly as the recalled Giroud sent in a low shot from 20 yards which forced Jussi Jaaskelainen into action, before Cazorla had a goalbound shot blocked.
West Ham looked to utilise Andy Carroll's presence whenever possible, but needed all the help they could get in their own penalty area as Arsenal continued to press. First, Carl Jenkinson's cross was hacked behind and then Carroll knocked Cazorla's fierce drive over his own crossbar.
West Ham, though, snatched the lead against the run of play in the 21st minute. The ball was worked down the left channel and Diame cut inside Aaron Ramsey to fire an angled drive into the top corner. Arsenal had a chance to equalise when Giroud just failed to connect with Per Mertesacker's flicked header through the six-yard box.
The French striker, though, did bag his Premier League goal four minutes before half-time. After winning the ball in midfield, Giroud stabbed it out to Lukas Podolski on the left. The German darted to the byline before cutting the ball back across goal - where Giroud arrived at pace to slot home.
The Irons were fired up following the restart, forcing a succession of corners. Wenger then replaced Gervinho with Theo Walcott, who almost helped set up a goal when Cazorla's shot hit Ramsey and bobble in West Ham penalty area, as his clever backheel was cut into the sidenetting by Giroud from a very tight angle.
The Irons went close moments later as Carroll knocked a deep cross wide after getting above Vito Mannone but Arsenal eventually broke away to take the lead as Giroud fed Walcott, who timed his run to beat the offside trap, dart into the penalty area and beat the keeper with a low shot into the near post.
West Ham quickly spurned a chance to draw level when Kevin Nolan blasted over from 10 yards, but it was game over when, in the 83rd minute, the excellent Cazorla finally got his goal - lashing a sublime left-foot effort into the top-right corner from 25 yards.