Alexandre Lacazette stepped off the bench to boost Arsenal's Champions League qualifying hopes with a VAR assisted winner in a 1-0 victory over West Ham
The Frenchman fired in from Mesut Ozil's headed cross (78) and, after a long VAR check, the initial offside flag on Ozil was overruled to put Arsenal on course for their third straight Premier League win, which moves them to within five points of fourth place
It was a tough blow for David Moyes' battling West Ham, who had hit the woodwork in the opening moments through Jarrod Bowen and seen Michail Antonio spurn a glorious close-range chance before forcing a superb stop from Bernd Leno in the second half
But Gunners manager Mikel Arteta will feel entitled to this valuable victory over his former Everton boss after Arsenal had two penalty appeals denied by VAR and hit the bar themselves through Sokratis in the first half
They are now closing in on fourth-placed Chelsea, while West Ham - who have lost six away games on the spin - remain out of the relegation zone on goal difference alone
West Ham, who had won just two of their previous 23 Premier League trips to Arsenal, came into this match on the back of a hugely important home win over Southampton and they showed their re-found confidence throughout an encouraging first half
They were almost ahead after just two minutes when Leno allowed Jarrod Bowen's shot from distance to burst through his hands and onto the post, before Antonio then failed to make the most of a West Ham counter-attack when he misplaced a pass to Sebastien Haller in the area
Arsenal - unbeaten in their previous seven Premier League games - had an early sight of goal themselves with a shot over the bar from Granit Xhaka and then also clipped the woodwork when Sokratis headed Pierre-Emerick Aubameyang's cross onto the frame of Lukasz Fabianski's goal
Chances continued to come at both ends, with Nicolas Pepe impressing with several wonderful dribbles past the West Ham defence, but it was the visitors who went in having missed the best opening - Antonio somehow hooking Issa Diop's knockdown wide from inside the six-yard box
Arsenal then had strong penalty appeals waved away in first-half stoppage time when Jeremy Ngakia appeared to clip Eddie Nketiah but VAR backed Martin Atkinson's decision to allow play to go on
The hosts came out strongly after the break with the impressive Bukayo Saka playing in Nketiah, who forced Fabianski into a point-blank block, but Leno then out-did his opposite number with a superb reaction stop to palm away Antonio's free header at the other end
Leno was worked again on 66 minutes, this time by Bowen, who had burst through the midfield, and VAR was back in action seconds later at the other end when sub Lacazette appeared to be pulled down by Diop - but once again, VAR opted not to change the on-field call of no penalty
The biggest VAR drama was to follow though, with the officials in Stockley Park eventually overruling the on-field decision to flag Ozil offside when he teed up Lacazette for the winner 12 minutes from time
 After a long delay the Arsenal players and supporters erupted in celebration when ref Atkinson signalled the decision had been changed
Arsenal held on during a frantic finale and are now eyeing an unlikely place in Europe's elite club competition next season, while West Ham continue to look over their shoulder at the drop zone
Arsenal manager : "We had the moments of luck we needed but as well it was because we had some really good individual performances at the back, sometimes to clear the ball, sometimes to make the save
 I'm really happy with the result because big teams find a way, when they don't have the best day - which is obvious, it wasn't our best day in terms of performance - they find a way to win it
"You can build from there and you can learn and you can take the positives and the negatives in a much better way
 The unity, the solidarity the players are showing, at the end it pays the price
 It didn't pay the price a few days ago when played Olympiakos here but it did today
"West Ham manager : "We didn't deserve to lose it
 In recent weeks we've made mistakes defensively which have cost us a goal
 Today I felt as if the mistakes came when we didn't take the chances
 Apart from that I thought the players did a great job, played very well, made several good chances but we couldn't convert them
 You couldn't fault the players for attitude
"Arsenal now travel to Manchester City on Wednesday for a Premier League clash live on Sky Sports, while West Ham are next in action next Sunday against Wolves - another game you can watch on Sky Sports
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