Gary Cahill and Cesc Fabregas were sent off as Burnley stunned nine-man Chelsea 3-2 on Saturday to ensure the Blues got their Premier League title defence off to a losing start at Stamford Bridge.
Chelsea were reduced to 10 men in the 14th minute when Cahill was sent off for a reckless challenge on Steven Defour, and they found themselves 3-0 down by half-time as Sam Vokes scored either side of a sensational Stephen Ward strike.
Substitute Alvaro Morata pulled one back in the second half, and he assisted David Luiz as Chelsea grabbed another, despite Fabregas picking up a second yellow card. But the Blues were unable to complete their comeback.
Burnley enjoyed a positive start as they displayed the hard work and organisation that kept them in the English top flight last season.
The Blues weren't troubled, though, until Cahill caught Defour with a high, studs-up challenge after the ball ran away from him in front of referee Craig Pawson, and the England international promptly received his marching orders.
Goal's Nizaar Kinsella believed the red card was fair, though the Telegraph's Matt Law might have been more inclined to give him a yellow:
Nizaar Kinsella @NizaarKinsella
I think he was sent off for the straight leg, a little high. Can't complain too much.2017-8-12 14:14:35
Matt Law @Matt_Law_DT
Looked a harsh red for Cahill to me.2017-8-12 14:15:39
Fabregas received a booking shortly after for sarcastically applauding Pawson, and proceedings soon got even worse for the hosts. After Vokes had a header disallowed because of an infringement in the buildup, he turned home Matthew Lowton's cross to give the Clarets the lead in the 24th minute.
Ward doubled the visitors' lead in spectacular fashion in the 39th minute when he controlled a lovely ball from Jack Cork on the left-hand edge of the area before shrugging off N'Golo Kante and lashing in a venomous effort past Thibaut Courtois.
Some sloppy defending allowed Vokes a second before the break, as he rose unchallenged to head home Defour's cross in the 43rd minute.
Per Squawka Football, the striker has begun the 2017/18 season as he finished the last:
Squawka Football @Squawka
Sam Vokes' last four Premier League games: ⚽️⚽️ vs. West Brom ⚽️ vs. Bournemouth ⚽️ vs. West Ham ⚽️⚽️ vs. Chelsea https://t.co/jwVErXAuDA2017-8-12 14:56:16
After the break, Chelsea sought a way back into the contest through Marcos Alonso as he drove the team's efforts from the left flank, and he twice tested Tom Heaton from distance. The latter was a free-kick that forced a superb stop from the Burnley goalkeeper.
Morata was the one who found the net when he escaped the attentions of Burnley's back four to glance home a diving header from Willian's cross in the 69th minute.
The Spaniard's eagerness cost his team minutes later, though, when he tapped in Andreas Christensen's goal-bound effort from an offside position.
Chelsea's comeback then ground to a halt when Fabregas was booked for a foul on Cork. ESPN FC's Liam Twomey examined the suspensions he and Cahill can expect:
Liam Twomey @liam_twomey
Unless it's overturned, that's a three-game ban for Cahill. Will miss Tottenham (A), Everton (H) & Leicester City (A) #cfc2017-8-12 14:20:45
Liam Twomey @liam_twomey
Fabregas sent off too now. Will also miss Spurs away next week & as it's two yellows, it can't be appealed #cfc2017-8-12 15:39:47
The Blues set up a tense finish when Luiz volleyed home Morata's flick-on in the 88th minute, while at the other end, Robbie Brady crashed a free-kick on to the post as Burnley desperately held on.
Morata's outstanding cameo is cause for optimism for the champions, but losing two players from an already-stretched squad will make the coming weeks difficult.