Chelsea slipped to a first loss in five games as goals for Ollie Watkins and John McGinn helped Aston Villa seal a 2-0 win in the Premier League on Saturday.
Watkins stunned the hosts early on with a lobbed first-half finish before his captain fired home a magnificent long-range effort close to the hour mark.
Defeat saw Graham Potter's previously resurgent hosts stutter at Stamford Bridge, leaving them five points off the top seven and potential European qualification.
For Unai Emery's visitors though, the result lifts them above their opponents and keeps them in with an outside shout of a surprise continental berth.
Chelsea rode their luck when McGinn rattled the crossbar with a fine volley, but they were less fortunate in the 18th minute.
A mix-up between Marc Cucurella and Kalidou Koulibaly allowed Watkins to dart in and lift a finish over the bemused Kepa.
Ben Chilwell thought he had an equaliser in first-half injury time when his header beat Emiliano Martinez at the left post, but referee Andy Madley chalked it off for a shove on Ashley Young in the build-up.
Matters worsened for the Blues in the 56th minute, as they failed to clear a corner and McGinn punished them with a sensational strike through a crowded box to double the deficit.
The hosts turned to N'Golo Kante, in his first appearance since last August, in an attempt to drag themselves back into the fight.
Yet Villa refused to simply sit back and see this one out, continuing to challenge their increasingly haggard opponents until the final whistle confirmed an impressive triumph.
