Chelsea 15th match unbeaten league run ended in South Wales this afternoon as the Blues went down 1-0 at the Liberty Stadium.
In truth the Londoners never looked like they were bothered and were outfought in every department by a Swansea side showing pride in their shirts.
The balance of the Chelsea side was wrong and as Chelsea's season edges into mid table oblivion, in-coming boss Antonio Conte has a major revamp needed to get them back even close to Premier League contention next season.
Gylfi Sigurdsson scored the only goal in the game on 25 minutes as Chelsea porous defence, minus John Terry, allowed the Icland midfielder the freedom of the park to slot home with a volley.
Sloppy play by Cesar Azpilicueta let in Angel Rangel for a fierce shot, on seven minutes which Asmir Begovic, in for the dropped 0 Courtois, did well to parry away.
The Blues had had the first effort on goal, on nine minutes, but Ruben Loftus-Cheek's right-footed effort, while on target, did not trouble ex-Arsenal stopper Lukasz Fabianski.
Baba Rahman sent across a daisy cutting byeline cross, but no Chelsea player anticipated the effort and it sailed across the Swans six-yard box.
Pato anticipated a cross from the right by Oscar but was unable to get the ball under control at the far post and it shinned off his leg of a goal kick.
The first goal came from sloppy play once again by Azpilicutea, on 26 minutes, allowing Montero to twist him inside out. He put in a cross which Matt Miazga weakly headed out and Gylfi Sigurdsson powered home with a left-footed volley past an unsighted Begovic from 12 yards.
Swansea should have doubled their lead on at least two occasions, - mix-up in the Chelsea rearguard the main factor. Only luck kept it level.
Pato had a great chance just before the whistle but shot wide.
Guus Hiddink Replaced Miazga at half-time for Kenedy. Mikel took over the vacted centre-back slot.
Pato should have scored on 55 minutes but a deft back-heeled flick from close range, from a Pedro pass, inched just wide of Fabianski's goal.
Pato's game ended on 65 minutes when Hiddink replaced him with Bertrand Traore.
Montero literally missed an open goal on 75 minutes when first Ivanovic and the Mikel failed to half Wayne Routledge's run. The winger clipped the ball over Begovic into Montero's path but the winger incredibly headed over the goal.
Loftus-Cheek then was replaced by Radamel Falcao, but that only served to illustrated the paucity of striking options for the Blues.
Next up for the Blues is a visit from Manchester City to the Bridge.
Asmir Begovic, Branislav Ivanovic, Cesc Fabregas, Baba Rahman, Oscar, Alexandre Pato, John Obi Mikel, Pedro, Matt Miazga, Cesar Azpilicueta, Ruben Loftus-Cheek
Subs Thibaut Courtois, Radamel Falcao, Bertrand Traore, Kenedy, Ola Aina, Kasey Palmer Charlie Colkett
Fabianski, Taylor, Williams, Fer, Paloschi, Ayew, Montero, Rangel, Sigurdsson, Cork, Fernandez,
Subs, Nordfeldt, Amat, Sung-Yung, Routledge, Gomis, Naughton, Barrow.
Referee Andre Marriner