Bafetimbi Gomis came off the bench to bag his first Premier League goal as Swansea City came from a goal down to stun Arsenal with a 2-1 win at the Liberty Stadium.
Two goals in quick succession from Gylfi Sigurdsson and Gomis turned the game on its head by the 78-minute mark after Alexis Sanchez had earlier fired the Gunners ahead.
The clash sparked to life on 20 minutes after a tentative start when Wilfried Bony looked to have a strong penalty appeal waved away by referee Phil Dowd.
Moments later, Jefferson Montero beat right-back Calum Chambers and almost caught out goalkeeper Wojciech Szczesny at his near post, but the Pole palmed it away.
It took 35 minutes before the game threw up a clear goalscoring opportunity, as Bony released Marvin Emnes - making his first Swans start - but the Dutchman blasted a shot straight at Szczesny.
The Gunners slowly but surely grew into the clash but waited until the final stages of the first half to test City's defence and goalkeeper Lukasz Fabianski.
First, Fabianski denied his former club by saving well from Danny Welbeck on 43 minutes following a slick one-two with Alex Oxlade-Chamberlain.
Then Ramsey - a former Cardiff City youth - almost silenced the Swansea boo boys at the death with a volley that just missed the post, while Per Mertesacker then headed wide in a barnstorming end to the half by Wenger's side.
Arsenal maintained that momentum throughout the interval and almost moved ahead minutes after the restart when Oxlade-Chamberlain fired at Fabianski.
They continued to toil in Swansea's half before finally finding the breakthrough on 63 minutes.
Santi Cazorla fed the ball out wide and found Welbeck, who chopped back to deceive Ashley Williams before teeing up the unmarked Sanchez to tap home the opener.
Garry Monk's side almost fashioned an immediate riposte, but Bony scuffed a left-footed shot wide of the mark from a promising position.
The Londoners never took heed of the warnings and Monk's troops soon turned the game on its head.
First, Sigurdsson fired a superb free kick beyond Szczesny on 75 minutes, before Montero stood up a fine cross for Gomis to nod home his first league goal just three minutes later.
The visitors pressed for an equaliser, but Swansea held out to bookend a miserable week for Arsenal, who surrendered a three-goal lead in their Champions League meeting with Anderlecht on Tuesday.