It didn’t last long, though, as the Swans equalised just a minute later when Alfie Mawson slid the ball through to Sam Clucas, who made no mistake with a calm finish past Cech.
And the Arsenal keeper was at fault for Swansea’s second when Shkodran Mustafi rolled the ball back to Cech and the keeper’s sliced clearance fell straight to Jordan Ayew to finish a gift-wrapped present.
There was still time for another as Clucas grabbed his second late on when he finished superbly from close range.