Hosts dominate as Vermaelen sees red
Premier League results/standings
The home side went into the game motivated by the prospect of going top of the table with a win, while Gianfranco Zola's men, having won only once on the road this season, would surely have wanted to take something out of the tie after seeing Wolves usurp them in the scramble for safety.
An early West Ham break saw Valon Behrami and Mido collaborate down the left hand side, but the Egyptian striker's cross was too high for veteran Guillermo Franco to control and convert into the first strike on goal.
Arsenal, on the other hand, were far more clinical than their local rivals, and found the net after just four minutes of play. Gael Clichy's surging run down the left resulted in a cross that was turned into the path of Denilson by Nicklas Bendtner, whose hold-up play afforded the Brazilian midfielder with the space to take a touch before lining up a low drive into the far corner.
The home side's confident opening continued upon the restart, and a second goal could have been added after a long range effort from Bendtner flew inches above Robert Green's goal before a sweeping one-touch move culminated in an acrobatic volley from Denilson that the England keeper saved with ease.
Whilst the visitors' defence left much to be desired, an Alessandro Diamanti free kick fizzed just over Manuel Almunia's crossbar, and a dangerous cross from Junior Stanislas that nearly found Mido at the far post warned the Gunners that they could not afford to be complacent despite a comfortable start.
A neat exchange between Alexandre Song and Cesc Fabregas created space in the middle of the pitch for Emmanuel Eboue to step forward and strike, but the Ivorian midfielder could only drag his shot wide with several West Ham bodies blocking the path to goal.
Arsenal's attacking play in the first half was, on occasion, a sight to behold, but several slick moves broke down at the final stage with a final ball lacking quality.
Likewise, the Hammers showed quality in possession and on the counter attack, but a dearth of assurance in the final third restricted their ability to test the redundant Almunia – exemplified when Diamanti turned inside to pass rather than strike after a clever Behrami flick saw him beyond the Gunners' backline.
The Italian striker, at the heart of most of West Ham's build-up play, found himself in the referee's book after kicking out in frustration following a flowing move that was abruptly halted by a two-footed - but fair - Sol Campbell challenge.
The Gunners passed with flair, but movement off the ball let down Arsene Wenger's side as a slide-rule ball saw Fabregas in the box with space, but the Spaniard – making a return from injury that has kept him out of the side for a fortnight – had no support in the middle, and his cross-cum-shot deflected wide for a corner.
West Ham should have punished Arsenal soon after as a long punt upfield bounced over and beyond Thomas Vermaelen, who was adjudged to have brought down Franco in the box, drawing a straight red from referee Martin Atkinson.
All eyes were on Diamanti, who stepped up to take the spot kick, but Almunia, called upon for the first time in the game, guessed correctly and pounded the ball away to the left of goal, much to the delight of the home support.
Arsene Wenger was visibly angered by the match officials, and the French boss loitered on the touchline as the first half came to a close, and proceeded to barrack the men in black as they walked down the tunnel.
Whilst not dignified in his protestations, the Arsenal boss may well have had a point as the penalty award was a controversial one as Atkinson was far away from the incident, dependent upon the inclination of his assistant Phil Sharp, and Franco went down under little pressure with the initial contact from Vermaelen appearing to be outside the box.
Zola, despite seeing his side fluff the chance to equalise from the spot, would have been by far the more satisfied boss heading into the dressing room, with his team bouncing back strongly from the early goal and facing a depleted opponent for the remainder of the game.
Arsenal adapted to the sending off though, with Song slotting alongside Campbell at the centre of defence, while Samir Nasri dropped deeper into the heart of the midfield away from Bendtner.
The second half began amidst a downpour of rain, and, as in the first half, a deluge of probing passing from Arsenal resulted in a chance for the hosts, as Andrey Arshavin headed over from a central position, but the Hammers again looked composed and content to draw the counter attack.
Former Chelsea striker Carlton Cole – left on the bench after nursing a knee injury – came on for Franco just ten minutes into the second half to add more power and potency to the visitors' forward play, whilst Wenger took the opportunity to readjust his side by bringing on Abou Diaby for Bendtner, leaving Arsenal with no orthodox striker as Arshavin adopted a central role.
Cole's introduction soon yielded a half-chance for Diamanti, but the Italian could only meekly deliver his effort from just outside the box into the arms of the falling Almunia.
Intricate work from Diaby on the edge of the box allowed Eboue to surge forward on the right, but with several players in the box the Ivorian's wayward cutback was met with frustration from his team-mates, who reasserted their authority on the game in a period of prolonged possession that kept the Hammers on the back foot.
But, in a mirror image of the first half, West Ham continued to probe and link-up well, with only a final touch of quality preventing Stanislas going through on goal after exchanging play with Cole. A Diamanti strike from range deflected wide, again hinting at signs of a comeback for Zola's struggling side.
However, the game soon petered out into a period of unusual disjointed play, but a leaping Campbell should have seen the home side take a two-goal lead, but the former Portsmouth man could only shoulder the ball into Green's arms with the goal gaping.
Both managers made changes with 15 minutes remaining, with South African striker Benni McCarthy replacing Mido, Mark Noble coming on for the ineffective Radoslav Kovac, and Bacary Sagna replacing Nasri on Arsenal's right hand side.
But it was the early substitutes who provided the greater influence on proceedings. Good work from Diaby enabled Arshavin to scamper into the box and fire at Green, whilst at the other end a clever turn allowed Cole to shoot from distance, but the stinging drive clipped the outside edge of Almunia's far post.
With ten minutes remaining, a forceful Arsenal move – involving the harrying Fabregas, who played a one-two with Eboue before bursting into the box – ended at the left hand of former Gunner Matthew Upson.
Atkinson on this occasion awarded the offender clemency, electing not to send off the already booked Upson, but Fabregas punished the Hammers from the same spot where Diamanti had failed to equalise.
With the lead cemented, Wenger hauled off the tiring Arshavin for Eduardo, and Arsenal rode out the remainder of the match with trademark assurance. Only a lashed effort from Cole provided any further scare.