Chelsea keeper Thibault Courtois was sent off as Chelsea made a shaky start to defending their Premier League crown.
Champions Chelsea twice threw away the lead at Stamford Bridge and were lucky to get a point as they finished the match with 10 men.
Courtois saw red after 52 minutes for bringing down last man Bafetimbi Gomis, who got up and beat replacement keeper Asmir Begovic with the resulting penalty.
That made it 2-2 and Swansea dominated the rest of the match having been unlucky to have been behind at all.
Chelsea started brightly but once the Swans settled they more than matched the home side.
So it was a shock when Chelsea took the lead on 22 minutes, Oscar’s free kick across goal beating everyone, including keeper Lukasz Fabianski.
But within minutes it was 1-1, Gomis and Andre Ayew combining to force two excellent saves from Courtois before Ayew’s deft drag back bought a yard and enough space for a shot into the corner.
Less than a minute later, Chelsea went ahead again. Willian’s cross took a deflection off the foot of defender Federico Fernandez and looped into the only bit of the goal Fabianski was not guarding.
After the red card, Swansea made great use of the extra man and posed a constant threat, leaving Chelsea to rely on counter attacks.