Swansea’s Pablo Hernandez struck a late equaliser as Chelsea rounded off another controversial week by losing their place at the top of the Barclays Premier League after a 1-1 draw.
The Blues have been embroiled in the furore over referee Mark Clattenburg's alleged inappropriate comments to John Obi Mikel, but they looked set to claim the spoils when Victor Moses nodded in his first league goal for the club in the 61st minute.
But Hernandez seized on Itay Shechter's pass to fire low beyond Petr Cech with three minutes remaining.
The Welsh side were bursting with confidence after their midweek Capital One Cup win against Liverpool at Anfield, and there was a swagger about their play during a first half they had the better of without really creating a meaningful chance.
Branislav Ivanovic, back from suspension, made a critical early intervention for the Blues to block Angel Rangel's pull back and deny Michu an effort on goal as Swansea started smartly.
It was wingers Wayne Routledge and Hernandez who were at the heart of many of Swansea's best moment and they were involved in a number of fine break-outs, one of which saw Mikel, who turned in a fine performance given the storm he has found himself at the centre of, make a brave block as Ki Sung-yueng fired at goal.
Chelsea highlighted their threat at the other end as Leon Britton cleared off the line from Fernando Torres' near-post header, which narrowly evaded the incoming Gary Cahill.
Moses' driven cross was then parried by Gerhard Tremmel, making his first Premier League start of the season, who also saved a weak follow up header from Torres.
Swansea's assurance in possession grew with Britton and Ki dictating play and Hernandez asking questions of Ashley Cole.
Michu could not connect with a De Guzman header as the hosts had difficulty breaking down a Chelsea backline well-marshalled by Ivanovic.
And the Blues slowly grew into the game with Eden Hazard becoming increasingly influential.
Ashley Williams was fortunate to escape any sanction when he appeared to force the Belgian over in the box, before the former Lille man freed Torres, only for Williams to get back and make a timely intervention.
Roberto Di Matteo brought on Ramires for the anonymous Oriol Romeu at the break and there was a marked improvement in the visitors' play.
Hazard cut inside to get away a low shot that Tremmel held well to his right, before Moses wasted a superb opportunity by heading over from Torres' cross.
Cole's excellent block denied De Guzman at the other end as the game opened up, but Swansea fell behind just after the hour mark.
Tremmel had saved Hazard's free-kick, but from the resulting corner Moses flicked Cahill's header in off the post.
Swansea boss Michael Laudrup quickly threw on Nathan Dyer and Danny Graham as his side sought an equaliser.
Neat interplay between Rangel and Ki ended with Cech gathering a high De Guzman shot, before the keeper tipped over an audacious attempted lob from Dyer.
Swansea pressed as Chelsea looked to preserve their advantage, and a deserved leveller finally came from Hernandez's placed effort before Graham was denied a winner by Cahill's excellent block.