A Neil Taylor own goal deep in injury time saw Chelsea deny Swansea another famous win as they scraped a 1-1 draw at the Liberty Stadium.
Former Blues winger Scott Sinclair had given Swansea a 39th-minute lead when his left-footed volley looped over Petr Cech and into the net, putting the hosts on course for a repeat of their stunning win over Arsenal.
Chelsea dominated the second half but they looked set to suffer a sixth defeat of the season when Ashley Cole picked up a second booking late on, but Jose Bosingwa's driven ball across the box struck the unfortunate Taylor and beat Michel Vorm.
Chelsea had Branislav Ivanovic to thank for saving them twice during a sluggish opening from Andre Villas-Boas' side.
Having survived that scare Chelsea began to take a stranglehold on the game, dominating possession and pinning Swansea deep in their own half.
Ashley Williams made a terrific interception to cut out Fernando Torres' intended pass to an unmarked Daniel Sturridge, while Juan Mata fired wastefully wide of either post after more patient build-up.
But after absorbing the pressure Swansea took the lead against the run of play as Sinclair netted against his former club.
Gylfi Sigurdsson's free-kick was weakly headed away by Bosingwa and a swing of Sinclair's left foot saw the ball float over Cech into the far corner.
Chelsea's frustrations were then compounded as Cole, who had been cautioned just before the interval, picked up a second booking for a rash tackle on Nathan Dyer and was dismissed.
But their pressure finally told as Bosingwa again tricked his way into the box and saw his driven effort strike Taylor to deceive Vorm and rescue a point.