With 10 men, tense and tentative it may have been at times, but Arsenal eked out the win that gives them the leadership and it could even be the shape of things to come as the season enters endgame.
Barcelona will pre-occupy them in the coming weeks for a mouth-watering Champions League quarter-final but alongside, the prospect of a Premier League title is edging from possible towards probable, even if Manchester United and Chelsea overtake them again on Sunday.
Making the points secure: Cesc Fabregas converts from the spot
After ailing Birmingham City at St Andrews next Saturday, Arsenal have Wolves at home on the day United and Chelsea meet. To follow, only Tottenham and Manchester City appear as form teams likely to interrupt a winning sequence that currently stands at six League matches.
It could also help that Saturday's events will not breed complacency but have instead confirmed that there is to them a new-found strength in adversity, on which they even seem to thrive.
After Denilson had given Arsenal a fifth-minute lead, the Emirates settled down for a goal feast but the sending-off of defender Thomas Vermaelen for a clumsy challenge on Guillermo Franco just before half-time meant that the script had to be rewritten.
Alessandro Diamanti saw his subsequent penalty saved by Manuel Almunia and it proved costly.
Letting fly: Denilson opened the scoring with a dazzling strike
Arsenal still had enough left on the break and Cesc Fabregas converted a late penalty his 18th goal of the season on his return after injury after Matthew Upson had handled.
'We've improved in our maturity and when we need to accelerate we can do it,' said Arsene Wenger. 'We are all conscious that we have won nothing yet but the hunger is there, the talent is there and the nerve is there.'
The manager and his team were fortunate, though, that West Ham were too limp to profit from their numerical advantage in the second half.
The Hammers four straight defeats now as they sink deeper in the relegation mire are in turn fortunate that Hull City and Burnley keep losing.
Marching orders: Martin Atkinson shows Thomas Vermaelen red
This week, they are at home against Wolves and Stoke and must surely start winning, even if it might take just 36 points to stay up this season.
'This week will tell us a lot,' said West Ham manager Gianfranco Zola. 'It is going to be massive.'
At least he will have back two key figures in Scott Parker and leading scorer Carlton Cole, the first held back on Saturday, the second appearing only belatedly.
Hands free: West Ham's Guillermo Franco holds off Sol Campbell
Zola's selection which hinted at keeping frontpowder dry duly looked weak initially and they made the worst possible start.
MATCH FACTSArsenal (4-2-3-1): Almunia; Eboue, Campbell, Vermaelen, Clichy; Song, Denilson; Nasri (Sagna 74min), Fabregas, Arshavin (Eduardo 84); Bendtner (Diaby 58). Subs (not used): Fabianski, Rosicky, Walcott, Silvestre. Booked: Campbell. Sent off: Vermaelen
West Ham (4-4-2): Green; Spector, Tomkins, Upson, Daprela; Diamanti, Behrami, Kovac (Noble 70), Stanislas; Franco (Cole 57), Mido (McCarthy 75). Subs (not used): Stech, Ilan, Ilunga, Spence.Booked: Diamanti, Kovac, Upson, Daprela.Referee: M Atkinson (West Yorkshire).
Backing off, they allowed Denilson to play a one-two with Nicklas Bendtner on the edge of the area and the Brazilian drilled a low shot into Robert Green's left corner.
It was the signal for some mesmerising attacking movement by the home side of the sort that West Ham legends from Ron Greenwood to Trevor Brooking would have purred over.
Arsenal were so nearly punished for failing to finish, however, and West Ham left cursing that they were not level at the interval when they should have been grateful they were just one goal behind.
Diamanti sent a high, hopeful ball forward for Franco to chase and Vermaelen appeared to claw him back. That was certainly the verdict of referee Martin Atkinson, who immediately pointed to the penalty spot and showed the Belgian the red card.
Full stretch: West Ham's Alessandro Diamanti (left) has his penalty saved by Arsenal goalkeeper Manuel Almunia
Almunia dived to his left to beat away Diamanti's kick and preserve Arsenal's lead but Wenger was still left fuming and waited by the touchline for Mr Atkinson as the half ended to remonstrate with him.
Wenger moved Alex Song into the back four for the second half a move he is likely to repeat next Saturday with Vermaelen now suspended and William Gallas still injured and Arsenal coped comfortably enough, thanks to West Ham's inability to move the ball quickly enough to drag the 10 men around.
Cole did hit the outside of a post with a shot but any Arsenal nerves evaporated when Fabregas flicked the ball up on to Upson's hand and Atkinson evened up the penalty count, the Spaniard tucking the ball home comfortably.
Arsene Wenger reveals 'little chance' Robin van Persie will return before season endArsenal 2 West Ham 0: As it happenedARSENAL FC