Neil Taylor's late own-goal saved 10-man Chelsea as the Swansea City defender denied his side a famous win.
Scott Sinclair returned to haunt his old club with a wonder goal as the ex-Chelsea winger whipped a left-foot effort over Chelsea keeper Petr Cech.
But after Ashley Cole was sent off, Jose Bosingwa made amends for his part in Swansea's goal by helping Chelsea rescue a point in added time.
His low strike deceived Swans keeper Michel Vorm after Taylor's deflection.
The Portugal international's last-minute cross-shot from the right-hand side of the penalty area was not goal-bound until the ball clipped Wales international Taylor and flew past a helpless Vorm.
The goal ensured fourth-placed Chelsea maintained their unbeaten start to 2012 but Andre Villas-Boas's side now trail Tottenham Hotspur in third by seven points following Spurs' .
Swansea, who would have moved back into the top 10 without Bosingwa's intervention in his 100th Chelsea start, had enough clear chances to win the game.
Danny Graham should have given the hosts, back at full strength after making 10 changes from their on Saturday, an early lead as he tried to pounce on a loose ball from Gylfi Sigurdsson's right-wing free-kick.
But just as the Swans striker was looking to shoot, Chelsea defender Branislav Ivanovic made a timely intervention.
Graham had an even better opportunity to score following a succession of errors in the visiting defence.
Blues keeper Cech's failed clearance dropped to the feet of Sigurdsson but his shot was cleared off the line by Ivanovic and Graham's goal-bound follow-up was also hacked off the line by David Luiz.
Swansea may have dominated the first half but it was Chelsea, through Daniel Sturridge, who had the best chance when the England striker swivelled to hit Luiz's low left-wing cross just wide of Vorm's left-hand post.
But after absorbing some sustained Chelsea pressure, Swansea took the lead thanks to Sinclair's stunner against the club he left 18 months ago.
Sigurdsson's free-kick was weakly headed away by Bosingwa and Sinclair swung his left-foot to send the ball over Cech and into the far top corner of the Chelsea net, the England under-21 international indulging in only muted celebrations against his old club.
It was Chelsea's turn to dominate after the break, substitute Michael Essien going close with a 25-yard drive early in the second half.
Bosingwa then teased his way to the byline but his hanging cross was headed clear by Angel Rangel, before another surge from the right-back saw Sturridge turn and poke wide.
Chelsea's pressure ensured Swansea struggled to get out of their own territory in the second half but in a rare late attack Kemy Agustien and Luke Moore combined to give Nathan Dyer a sight of goal, but he dragged his shot across the face.
Swansea must have felt they had secured a second successive memorable home triumph - having at the Liberty Stadium - when England left-back Cole, who had been cautioned just before the interval, collected a second yellow for a rash tackle on Dyer.
Chelsea, though, never relented as Bosingwa again tricked his way into the box and his driven effort found its way to goal via Taylor.