It was a bold old statement of Arsène Wenger's to suggest that it will do Arsenal good to compensate for Robin van Persie's goals by sharing the load around his newly assembled front line. His team rose to the challenge at the Boleyn Ground, with a first Premier League goal for Olivier Giroud and fine strikes from Theo Walcott and Santi Cazorla crowning a valuable away win.

Having suffered a setback last weekend with a performance against Chelsea that left Wenger complaining about a lack of personality, Arsenal responded with character. Confronted by an old nemesis in the shape of a Sam Allardyce team that backed them into an awkward corner by opening the scoring, the Gunners struck the right combination of force and finesse. They remain unbeaten away and continue to play some compelling football on the road.

For all the talk of the damage a direct approach could inflict on an Arsenal team that have crumbled at set pieces lately, West Ham struggled to load too much pressure on a side benefitting from the reintroduction of the assured Per Mertesacker. Although Andy Carroll was an imposing presence, the home team were unable to mount a sustained offensive. "You can never control him for 90 minutes, but we fought with him," Wenger said.

The selection of his own big target man – and it was Giroud's first league start for more than a month – ensured West Ham also had plenty to concern themselves with. The former Montpellier striker's all round contribution was impressive. Several attempts on target, a goal and an assist is no bad return for an evening's work.

With Arsenal even looking dangerous from the set piece, West Ham duly took the lead with some virtuoso skill. So much for stereotypes. In the 21st minute, George McCartney fed the ball to Mohamed Diamé, who powered into the box, leaving Aaron Ramsey in his wake, and bent the ball ferociously into the far corner of the net. It was a marvellously executed finish from the huge Senegalese, who celebrated his first goal for the club with such relish he was cautioned after throwing himself into the crowd. He can count himself lucky as, shortly afterwards, he recklessly careered late into Mikel Arteta, but the referee, Phil Dowd, elected not to reach for another card.

The goal knocked Arsenal out of their stride and it was the man who had been struggling most obviously for confidence who grabbed Arsenal by the scruff of the neck to get them back into the game. Giroud gathered the ball in midfield, arced a pass out to Lukas Podolski and sprinted in front of his marker to lash the return ball past Jussi Jaaskelainen. West Ham had opportunities to retake the advantage, with Kevin Nolan twice in shooting range and Carroll outjumping Vito Mannone, but neither player could quite find their range.

Both teams jostled for position after the break. West Ham had to readjust around the hour mark when Ricardo Vaz Tê dislocated a shoulder as he rashly challenged Mannone. Allardyce's initial assessment was an absence of between six to 12 weeks. Kieran Gibbs was another injury concern after suffering a thigh problem and is very doubtful for the England squad.

Walcott, who started on the bench yet again but came on to provide another example of why he yearns for a striking role, played a critical part in the comeback. Giroud's deft assist set the fleet-footed attacker bearing down on goal. The finish was instinctive and ruthless, as Walcott passed the ball beyond Jaaskelainen. Message received and understood? We'll see.

Allardyce was left frustrated. "The second goal was a killer because we were in a fantastic position to score at that stage. Because we picked up the wrong pass, we've opened ourselves up and they've severely punished us on the break," he conceded.

The clincher came from a player who has become integral to Arsenal. When Walcott found Cazorla with a flick, the Spaniard arrowed a brilliant, precision third from 25 yards out. Since the beginning of last season no player from Europe's top leagues has scored more often from outside the box than Cazorla. "He's taken the Premier League by storm," Walcott said. "He's fantastic to play with every day. He's our conductor. I don't even know what foot is his best to be honest." Either, or both, are proving to be a considerable weapon.