Aston Villa 1 Chelsea 0
Chelsea, who ended the match with nine men, had their lead at the top of the Premier League cut to six points and saw a late Fabian Delph winner settle an eventful encounter.
Jose Mourinho’s side largely dominated possession and territory but lacked a cutting edge and the controversial sending off of Willian midway through the second half seemed to tip the balance in Villa’s favour.
The Brazilian, in tussling with Delph, was given a second yellow card by referee Chris Foy, who had earlier ruled out Nemanja Matic’s goal.
Delph’s cute finish from a Marc Albrighton pass eight minutes from time completed a miserable day for the Blues, who also had Ramires sent off late on.
An intriguing first half, which saw the skill and guile of Chelsea matched closely by the home side’s honest endeavour, saw chances at both ends.
The Blues looked the more likely to score, with recalled Brazilians Oscar and Willian both firing narrowly wide.
But Christian Benteke was a threat on the break and he hooked a volley just wide of Petr Cech’s far post.
Chelsea thought they had broken the deadlock late in the first half when Matic bundled in.
But their celebrations were cut short as Foy and assistant Peter Banks spotted a handball as Matic controlled the ball.
The visitors then spent large spells of the second half encamped in Villa territory but their final ball was often found wanting.
In spite of their dominance, they struggled to carve out clear chances with Eden Hazard allowing Karim El Ahmadi a clearance inside the six-yard box when he chose to pass instead of shoot.
Hazard later found Oscar with a short corner but the Brazilian’s tame shot was comfortable for Villa keeper Brad Guzan to gather.
At the other end, Benteke swept a shot just wide of the post after being found by Andreas Weimann.
Then came the crucial incident which swung the match, as Willian was deemed to have pulled back Delph and earned a second yellow card.
Villa grew in confidence with the extra man and with 82 minutes on the clock they snatched what proved to be the winner as Delph sent a terrific first-time backheel past Cech.
The Chelsea keeper was then called upon to keep out Benteke and a further effort from Delph, before Ramires walked after appearing to stamp on the leg of Karim El Ahmadi.
Chelsea boss Jose Mourinho was also sent off after protesting.
Foy has now sent off six Chelsea players, plus Mourinho, in his last eight matches involving the Blues.
Chelsea (4-2-3-1): Cech; Ivanovic, Cahill, Terry, Azpilicueta; Matic, Ramires; Willian, Oscar (Schurrle 67), Hazard; Torres (Ba 67).
Subs not used: Schwarzer, Kalas, Mikel, Lampard, Salah.