Andy Carroll scored a hat-trick in under ten minutes either side of half time as West Ham all but ended Arsenal’s fading title hopes.
The Gunners were in complete control at Upton Park after goals from Mesut Ozil and Alexis Sanchez but, as the interval approached, Carroll’s physical presence was too much for Arsene Wenger’s team.
The big striker netted a quick brace in the closing moments of the half and then headed the Hammers in front on 52 minutes.
Laurent Koscielny rescued a point for Arsenal 20 minutes from the end but, in truth, a point does little for either team’s end of season aspirations.
Arsenal trail Leicester by ten points while West Ham are now a point behind fifth-placed Manchester United, with both chasing teams having played a game more than their rivals.
Manuel Lanzini looked set to get West Ham off to a flyer when he nodded in from close range after 15 minutes but the offside flag denied him.
Moments later and Arsenal pierced West Ham’s defence to take the lead.
Alex Iwobi found Ozil in space behind the Hammers cover and he slid the ball past Adrian.
On 35 minutes, the visitors helped themselves to a carbon copy, Iwobi this time picking out Sanchez to double the advantage.
Wenger could have been forgiven for thinking his side were on their way to victory before Carroll spectacularly intervened.
In the final minute of the half he headed home Aaron Cresswell’s cross from six yards out.
With Arsenal still reeling, Carroll was then afforded time to control on his chest after a cross from Mark Noble found him and, at the second attempt, he stabbed past David Ospina to level the game in first half stoppage time.
There was more to come.
Seven minutes after the break, Michail Antonio stood up a teasing cross at the back post and Carroll powered a header into the net despite the best efforts of Gabriel on the line.
The hat-trick took just nine minutes and 50 seconds to complete.
To their credit, Arsenal responded as Wenger threw on Aaron Ramsey and Olivier Giroud to seek a way back into the game.
It was Koscielny that made the breakthrough. Ozil’s cross was deflected into the Frenchman’s path by Danny Welbeck and the defender steered the ball high into the corner with a clever finish.
Both sides sought what would have been a vital winner but in the end a stalemate ensued, much to the frustration of both Wenger and his opposite number Slaven Bilic.