Northern Ireland international Chris Brunt thunderbolt adds gloss to West Brom's victory over Chelsea
West Brom 3-0 Chelsea
Cesc Fabregas' bizarre red card capped a wretched night for Chelsea as the champions were shocked 3-0 by West Brom.
Saido Berahino's double ended his own nine-game drought as he made it 20 goals for the season for the Baggies.
Chris Brunt added a third to compound Chelsea's miserable evening in the West Midlands as their 16-game unbeaten league run ended.
And Fabregas' first-half dismissal will go down as one of the most mindless in the history of the Premier League.
The midfielder saw red after kicking the ball against the side of Brunt's head as referee Mike Jones took control of a clash between fellow Northern Ireland international Gareth McAuley and Diego Costa.
Blues boss Jose Mourinho disagreed with the decision. He said: "It was nothing special - one of the top referees would resolve the problem with words, but Mike decided to give the red card which I disagree with completely."
He also commented that the result was not a big shock to him. He added: "I cannot say it's a big surprise for me. I know what happens when a team are champions with matches in hand. When you're champions so early it's difficult to keep the motivation high.
"When you lose that salt and pepper of the competition it's difficult to compete at the highest level. If I have to blame anybody, blame Man Utd, Man City, Arsenal and Liverpool for letting us win the title so early!"
Chelsea rarely threatened, even before Fabregas walked, although Loic Remy hit the post in the second half.
They had been boosted by the return of Costa after a six-week lay off with a hamstring problem while Nemanja Matic also returned with Gary Cahill, in after Kurt Zouma's season-ending knee injury.
Berahino, Callum McManaman and James Morrison were recalled by Albion and McManaman nearly fired them into a fifth-minute lead.
Boaz Myhill then claimed Fabregas' shot after the midfielder had wriggled through, before the Baggies took the lead in spectacular style in the ninth minute.
Berahino received the ball 25 yards out and allowed it to roll across him before arching a first-time drive into the bottom corner.
Matic drilled wide in reply but the organised Baggies comfortably kept Chelsea at bay.
But a routine night flared up in curious fashion when Fabregas was sent off after 29 minutes.
It began when Costa and McAuley grappled in the area, with the Chelsea striker booked after the pair squared up to each other.
And while referee Jones was calming the situation down Fabregas - from 20 yards away - kicked the ball towards the group and against the side of Brunt's head.
Darren Fletcher then squared up to the midfielder before Fabregas was sent off, his first red card since January 2006.
It was stupid from the former Barcelona star but gave the game much-needed bite. Fletcher was booked for his part in the incident.
Remy dragged a shot wide at the end of the first half but Chelsea were 2-0 behind before they could even blink after the break.
Just 26 seconds after the restart, John Terry scythed down Berahino in the area and the striker beat Thibaut Courtois from the spot.
Remy thumped the post from 20 yards but it was only a brief threat and Brunt sealed Albion's victory on the hour.
Chelsea switched off from a short corner and the midfielder was allowed to run into the box and lash past Courtois and condemn Chelsea to just their third league defeat of the season.
West Brom: Myhill, Dawson, McAuley, Olsson, Lescott, Fletcher, Yacob, Morrison (Baird 89), McManaman (Gardner 54), Berahino (Ideye 79), Brunt.
Goals: Berahino 9,47 pen, Brunt 60.
Yellow cards: Fletcher, Olsson, Gardner.
Chelsea: Courtois, Ivanovic, Cahill, Terry, Luis, Loftus-Cheek (Ake 73), Matic, Remy (Brown 79), Fabregas, Hazard,
Costa (Cuadrado 64).
Yellow cards: Costa, Cuadrado.
Sent off: Fabregas (29).
Referee: Mike Jones (Cheshire)