Alexis Sanchez scored a hat trick as Arsenal thrashed West Ham 5-1 at the London Stadium to move up to second in the Premier League table.
Sanchez hit all three goals in the second half, with Mesut Ozil and Alex Oxlade-Chamberlain also getting on the score sheet, as the Gunners climbed to within three points of leaders Chelsea, while the Hammers remain just a point above the drop zone after a sixth game without a win.
Arsenal started the match brightly, working especially well down the left with one Nacho Monreal cross just being intercepted at the far post with Sanchez waiting to pounce.
Shkodran Mustafi had the chance to edge the Gunners into the lead in the 17th minute, heading wide from a corner with both Laurent Koscielny and Sanchez unable to divert the ball in.
West Ham created their first opportunity of the game soon after with Manuel Lanzini dancing past two defenders only to be denied by a good save from Petr Cech at his near post.
Arsenal, however, found the breakthrough in the 24th minute as Sanchez raced onto a loose ball after a mistake at the back from West Ham, with the Chilean then teeing up Ozil to finish into an empty net for his eighth goal of the season.
The visitors could have been two up six minutes later but Oxlade-Chamberlain wasted the opportunity, firing high and wide when Theo Walcott was unmarked at far post.
A dominant Arsenal continued to go in search of a second with Sanchez at the heart of their attacks -- the forward seeing one long-distance hit saved by Darren Randolph, before then attempting to round the Hammers keeper after being played in by Oxlade-Chamberlain, only for his heavy touch to let him down.
A subdued West Ham did manage to create a chance to equalise just before half-time, but Pedro Obiang could only head Ashley Fletcher's cross over the bar when in a good position to do better.
Arsenal started the second half on the front foot and Walcott had the chance to grab a second for his side shortly after the restart, only to head Ozil's free kick just over bar.
Walcott was soon presented with another chance when put through on goal but Edimilson Fernandes was able to track back and make the tackle, while down the other end Laurent Koscielny made a vital interception to cut out a Lanzini ball.
Buoyed by the home support, West Ham were on the attack again in the 55th minute with Fletcher rifling a shot just wide from the edge of box.
Arsenal, now being forced to play on the counterattack by West Ham, created a chance in the 65th minute when Sanchez fed the ball to the unmarked Walcott, but Angelo Ogbonna did brilliantly to recover and get the block in on the winger's strike.
The Gunners pushed forward again on the hunt for a second goal with Monreal picking out substitute Aaron Ramsey in the box but his strike was blocked, before Ozil then had his rebound well saved by Randolph.
Arsene Wenger's side did manage to double their lead in the 72nd minute through Sanchez, who sublimely turned his marker before bursting past another Hammers defender and firing into the far corner of the net with a great strike.
And Sanchez then made sure of the result with his second goal of the evening eight minutes later, picking out the bottom corner from the edge of the box with a fine hit.
West Ham managed to pull one back in the 83rd minute through substitute Andy Carroll, who was on hand to head home the rebound after Dimitri Payet's free kick had come back off the bar.
But Arsenal restored their three-goal advantage just a minute later, with Oxlade-Chamberlain bending a shot past Randolph from the edge of the box.
And there was still time for a fifth for the visitors as Sanchez completed his hat trick in the 86th minute, racing onto Oxlade-Chamberlain's pass before giving Randolph the eyes and dinking the ball over him for his 13th goal of the season.