A frustrating afternoon for West Ham United saw Manuel Pellegrini’s side fall to a 3-1 defeat at the Emirates Stadium.
The Hammers took the lead thanks to an excellent goal from Marko Arnautovic; something the away side deserved following some brilliant play.
However, Arsenal were level just four minutes later thanks to Nacho Monreal’s finish.
The Irons continued to press in the second period but fell behind on 70 minutes as Alexandre Lacazette’s strike went in off defender Issa Diop.
And a final blow was inflicted in the closing moments as Danny Welbeck netted from close range.
The end-to-end contest began with both teams enjoying possession of the ball, with the away side in particularly taking advantage of space on the flanks.
Arsenal did put the ball in the net on 12 minutes, as Aaron Ramsey headed home after Fabianksi made a terrific save to deny Henrikh Mkhitaryan, but the Welshman was ruled offside.
Arnautovic then eluded Arsenal’s offside trap, courtesy of well-timed pass by Robert Snodgrass, but his driven effort was wide at the near post.
It was the Austrian who opened the scoring however, as the 29-year-old netted with a low finish from just outside the penalty area, having combined superbly with Felipe Anderson to create space in the Gunners half.
West Ham’s deserved lead was taken away just four minutes later, when Hector Bellerin’s low cross had too much pace on it for the Irons defence to reach. The ball fell to Monreal, who had time to pick out his spot and score.
Despite Arsenal’s equaliser, West Ham were not deterred, and enjoyed the better chances in the remaining time in the first half. First, Anderson played Michail Antonio through on goal, but the No30 opted to shoot from 22 yards, and his attempt was saved.
It was then West Ham’s turn to have a goal ruled out for offside. A fantastic counter-attack, started by Anderson, resulted in Snodgrass sending Arnautovic into a one-on-one position. Although the No7 scored, the linesman’s flag had been raised.
Antonio saw a curling effort go just wide of the far post and, as extra time in the first period ticked over, Snodgrass received the ball inside the area following some sensational play on the edge of the penalty area. The Scotsman’s low effort seemed destined to find the net, but Cech got down to deny the No11.
Just a few moments into the second half, and Arsenal had the chance to take the lead. Shkodran Mustafi directed a fierce header towards goal, but Fabianski was again equal to the effort.
Arnautovic struck a left-footed shot after some excellent work by Anderson, but last season’s Hammer of the Year appeared to pick up a knock in the move, and was replaced by Chicharito.
Former Gunners Lucas Perez also entered the fray for West Ham, and a powerful effort from Anderson almost fell to the Spaniard after Cech failed to deal with it, but the ball was cleared
On 72 minutes, Pellegrini’s side fell behind in the most frustrating of ways, as a wild cross from Lacazette struck Diop in an awkward position. Neither the defender or Fabianski could stop the ball from bouncing into the net.
West Ham continued to press, searching for an equaliser that would give the team the deserved point that the performance deserved.
It seemed that moment had come as extra-time began, as Chicharito rose to head a Ryan Fredericks cross. The ball fell to Anderson, and his low cross seemed set to find a Hammer, but substitute Andriy Yarmolenko couldn’t connect.
And a devastating, cruel blow was inflicted just seconds later, as Welbeck turned from close range to secure the points for Arsenal.
Arsenal: Cech (c); Bellerin, Mustafi, Sokratis, Monreal; Guendouzi (Torreira 55), Xhaka, Iwobi (Lacazette 46), Ramsey, Mkhitaryan; Aubameyang (Welbeck 75)
Subs not used: Leno, Holding, Lichtsteiner, Elneny
Goals: Monreal 30, Diop OG 70, Welbeck 90+2
West Ham United: Fabianski; Fredericks, Balbuena, Diop, Masuaku; Sanchez, Wilshere Snodgrass (Yarmolenko 75), Anderson, Antonio (Lucas Perez 62); Arnautovic (c) (Chicharito 58)
Subs not used: Adrian, Zabaleta, Rice, Obiang
Goals: Arnautovic 25