Arsenal 5 West Ham 1: Olivier Giroud scores brace as Gunners restore pride with second-half blitz

A frenetic 10-minute spell after the interval saw the home side score four times, putting beyond any doubt a game that had hitherto been finely poised at 1-1.

Jack Collison had given the visitors the lead early in the first half, a goal that was soon cancelled out by Arsenal's Lukas Podolski. The German was then instrumental in a second-half onslaught that offered shades of Arsenal at their best as Olivier Giroud plundered a double, and Theo Walcott and Santi Cazorla also claimed a goal each.

For West Ham, there was little joy. They scored their sixth away league of the season, but finished the match with 10 men when, having already used up their three substitutes, Daniel Potts was stretchered off with what appeared to be a nasty head injury.

The 18-year-old had not been on the pitch for long and such was the length of his on-pitch treatment that the fourth official added 12 minutes of injury time.

The long delay took the sting out of a contest that, for West Ham, had been in danger of turning into a humiliation. There was still half an hour of the match still to go when Arsenal went up 5-1, but for the time being Arsene Wenger's men will be pleased to have closed the gap on fourth-placed Tottenham to four points.

The Gunners revamped their midfield for the match in light of injuries to Abou Diaby and Francis Coquelin. In came Aaron Ramsey, while Podolski also returned after missing the defeat to Chelsea on Sunday.

The Irons make four changes as Matthew Taylor, Carlton Cole, Ricardo Vaz Te and Collison all started, while recent signing Joe Cole was left on the bench. Rumoured Arsenal transfer target Mohamed Diame was also left warming the pine.

The visitors entered the match on a dire run of form, with only one win in their last nine in all competitions. Arsenal, too, were amid an equally inauspicious spell, having not won in the league since December 29 when Newcastle were trounced 7-3.

However it was the Irons who looked the most likely to arrest their bad run when Collison drove a scorching shot past Wojciech Szczesny on 18 minutes. The opportunity had come from a Taylor corner, which was cleared only to the edge of the box by Giroud. Collison seized the opportunity with real panache, catching the ball on the half volley and leaving the Polish custodian with no chance.

The Irons bench erupted and manager Sam Allardyce, who before kick-off denied an FA misconduct charge following comments made to the media in the wake of his side's FA Cup exit to Manchester United last week, punched the air in delight.

The visiting fans, who had already goaded their hosts with chants of "You're ground's too big for you" – a reference to the swathes of empty seats around the stadium — were soon silenced though when Podolski scored with a rasping shot from 22 yards that beat Jussi Jaaskelainen all ends up. The ball had made its way to the German following a series of square passes from Bacary Sagna, Santi Cazorla and Wilshere, but the sheer force of the finish made up for any lack of invention in the build-up.

Arsenal should have taken the lead on 35 minutes. Kieran Gibbs cut the ball for Podolski, but it fell on the German's weaker right foot and his scuffed effort was cleared off the line by Joey O'Brien.

Moments later Arsenal were performing a similar escape job, Ramsey clearing from Carlton Cole after the Hammers forward had nipped in to take advantage of a poor Sagna clearance. In fairness Sagna was a little unlucky as his attempt smashed into the head of Taylor, in doing so sending Cole clear.

Nonetheless it was Arsenal who ended the half on top, Cazorla forcing Jasskelainen to scramble across his goal to parry away a free kick that had appeared destined for the top corner.

Whatever Wenger said to his players at half-time, it worked. His charges played the opening of the second stanza as if their careers depended on it and they nearly took the lead straight from the restart. Walcott found space down the right flank and crossed for Jack Wilshere in the area, but O'Brien just got back in time to cut it out.

The breakthrough soon came, on 47 minutes. Walcott whipped in a corner to the near post and Giroud escaped his marker to power a volley into the roof of the net.

The Gunners sensed blood and were soon 3-1 up — and in some style. Giroud lobbed a ball over the Hammers defence to Podolski who poked the ball to Cazorla, who was to his right. The Spaniard looked like he would struggle to get a clean shot away and had two defenders around him, but he conjured a Johan Cruyff-style flick to finish.

The Irons did not know it, but the blitz was far from over. Within seconds, the home side produced yet another lightning break from the edge of the halfway line, with Podolski rampaging down the left flank before crossing to Walcott, who had run half the length of the pitch, at the back post to finish.

It was breathtaking stuff. West Ham suddenly seemed under threat every time Arsenal had the ball. Allardyce cut a stunned figure on the touchline. The Irons fans still sung defiantly, but were soon drowned out by the roar of the home fans when Giroud slid home his second and his side's fifth, completing a incredible burst of four goals in 10 minutes. Podolski again turned provider, driving down the left flank before laying the ball on a plate for Giroud, who gratefully netted his 11th goal of the season.

The worry for the visitors was that there were still 30 minutes left on the clock and Arsenal seemed intent on scoring more. Allardyce replaced Winston Reid and Collison with Daniel Potts and Alou Diarra.

Amid the onslaught Wenger had also withdrawn Thomas Vermaelen for Laurent Koscielny, the Belgian still limping from a knock he picked up in the first half. Arsenal's standout performer Podolski was soon withdrawn for Andre Santos. In the same round of substitutions Irons forward Vaz Te, who had earlier received a rollicking from Allardyce for running offside, was replaced by Diame, who received a generous round of ironic applause from the home fans.

The changes did not seem to be improving the Irons' fortunes. At one stage they found themselves on the wrong end of a four-on-one situation, which Walcott failed to make the most of as his cross struck Diarra.

However the game would take an unexpected turn when Potts clashed heads with Sagna and he lay seemingly unconscious for several minutes before he was stretchered off to generous applause.

Potts stayed in hospital overnight and was set for further tests today. A statement on the club's official Twitter feed read: "West Ham United can confirm that Dan Potts will undergo scans and further assessment in hospital on Thursday.

"On behalf of Dan, the club would like to thank fans for all their messages of support for the defender and join them in wishing him well."

The Irons remain 12th and, having gone out of the Cup to United, do not play again until next Wednesday when they travel to Fulham. Arsenal face Brighton in the FA Cup fourth round this Saturday with a degree of confidence restored.