Thierry Henry struck six minutes from time as Arsenal came from behind to claim three vital points with a 2-1 win over West Brom at The Hawthorns.
The Gunners will count themselves fortunate to have escaped the Black Country with their Premiership lead intact after a mighty effort from Gary Megson's men.
Henry nipped into beat Russell Hoult from close range after Adam Chambers' attempted clearance fell for him.
Albion ought to have stolen the match before Henry's decisive strike when Jason Roberts beat David Seaman with a low shot which bounced to safety off the base of the goalkeeper's right-hand post.
Albion's transfer-listed striker Daniele Dichio had headed his side in front after just three minutes of a storming encounter.
But the Gunners responded at the start of the second period when recalled striker Francis Jeffers took advantage of a slip by Sean Gregan and poked the equaliser past Hoult.
Jeffers had only returned because of the loss of cold victim Freddie Ljungberg and boss Arsene Wenger was boosted by the return after a groin strain of his captain Patrick Vieira.
But Albion's storming start had the Gunners on the back foot immediately with Martin Keown giving away an unnecessary corner with just nine seconds on the clock.
Koumas' set-piece sparked a spell of pressure which eventually led to Albion's stunning opener.
Dichio had already come close in the second minute when he rifled a rising shot from 25 yards which the back-pedalling David Seaman did well to tip over his bar.
But Seaman was unable to do anything about Dichio's opener less than 30 seconds later when he rose above the Gunners` rearguard and powered his header into the back of the net.
It was Dichio's third goal in three consecutive home matches - all since being transfer-listed by Megson because of a poor run of form.
Arsenal slowly settled and started to enjoy the majority of possession without truly troubling Hoult throughout the opening spell.
Hoult did spill a Giovanni van Bronckhorst cross but the returning Ronnie Wallwork booted clear.
Lauren looked a particular danger down the right and he lofted an excellent cross towards van Bronckhorst in the 13th minute which Hoult did well to hold first time.
Then Sol Campbell went upfield but headed well wide from Henry's corner.
Cole and van Bronckhorst were starting to find the Albion box with ease and only some fine last-ditch challenges from Sean Gregan and Larus Sigurdsson kept Albion's lead intact.
Vieira fired well wide from 25 yards after a neat one-two with Lauren on the right, then Wiltord beat the inexperienced Adam Chambers on the opposite flank and chipped in a cross which Hoult had to tip over his own bar.
Van Bronckhorst just failed to meet Wiltord's cross from the right moments later as Arsenal piled on the pressure, and Henry beat Larus Sigurdsson before scuffing a poor shot into Hoult's arms.
Albion soaked up the pressure and could have gone in at half-time further ahead when Roberts bustled into the box from the left and fed Dichio, who mis-kicked.
But just as Albion had taken the first half by the scruff of the neck, Arsenal piled on the pressure straight after the re-start.
Hoult brilliantly turned a rising van Bronckhorst shot around his post before Sean Gregan failed to deal with a Henry cross from the left leaving Jeffers free to bundle the ball over the line for the equaliser.
Sigurdsson could have put Albion back in front in the 56th minute when he met a Koumas corner but header inches wide of Seaman's right-hand post.
Jeffers was denied by a timely interception from Moore at the other end as Arsenal continued to stream forward in search of three more priceless points.
Vieira tried a lofted ball into the box towards van Bronckhorst at the far post but the alert Hoult came off his line to catch under pressure.
Henry shot straight at Hoult when he could have done better before Roberts missed a glorious opportunity for the home side to re-take the lead.
He bustled past Keown into the box and struck a low shot which beat Seaman but ricocheted off the base of the goalkeeper's right-hand post and Lauren gratefully swept up the danger.
Henry shot dreadfully high and wide from 10 yards as substitute Robert Pires stretched the Albion defence again, before he grabbed his chance six minutes from time to keep his side's Premiership title dream firmly on track.
Match-winner Thierry Henry praised the 'commitment and aggression' which proved crucial in the Gunners' hard-fought victory.
'After the first half we thought we didn`t deserve anything
other than to be 1-0 down,' said the French international.
'At one point I said "it is going to be a tough one today" and in the second
half we had to show another face of Arsenal, to play football and fight - and
that's what we did.
'I think commitment and aggression was missing in the first half - but we
showed it in the second half.
'When a team is fighting to not go down they always come at you like crazy -
and West Brom played some brilliant football early in the game.'
Henry screwed a good opening wide before netting the winner five minutes from
time and he explained: 'I knew I had to do something.
'But the important thing is the reaction after. There was still time to go
and you have to pick yourself up.'
Arsenal boss Arsene Wenger paid tribute to Albion's battlers.
after the Gunners came from behind to snatch three points at The Hawthorns.
Wenger said: 'West Brom's game plan worked marvellously well and they were
'It surprised me that West Brom made no defensive mistakes apart from the
second goal which was more down to fatigue.
'But we were mentally very determined today. A normal Arsenal team might not
have won this game - today we had the mental strength to change things, we
really wanted it and we got it.'
Albion boss Gary Megson took no comfort from another battling Baggies display
which went unrewarded.
He said: 'The effort is there, the competing and the battling - all that type
of stuff. But it's not a great deal of solace when you've lost another home
'I can't complain about us having a go today and there was a lot on the
'We looked a threat from set-pieces but our passing had to be seen to be
believed. We've shown nowhere near the quality that we've got.'