Gareth McAuley's error cost Albion as the Baggies continued their poor form at Stamford Bridge.
Diego Costa stole the ball off McAuley and fired home past Ben Foster in the game's only goal in the 75th minute.
Here's what the press had to say about Albion's spirited defeat. Click on the link to read the full report.
A Diego Costa strike 14 minutes from time ended West Bromwich Albion’s resistance and earned Chelsea a ninth straight win.
The league’s top scorer, who had been quiet by his standards, fired into the top corner after Gareth McAuley dwelt on the ball.
The timing of the goal was cruel, even if Chelsea arguably deserved the points on the balance of play and chances created.
For 76 minutes, the plan was working to a tee. Albion were grinding out a well-earned point against the league-leaders thanks to the discipline of Matt Phillips and Chris Brunt.
They were frustrating Antonio Conte's team, and creating their own chances on the counter attack.
But then, Diego Costa struck. Pouncing on the slightest of errors by Gareth McAuley, the Spaniard wriggled free from the touchling and curled a stunning finish into the top far corner.
Pulis played a 4-2-3-1 with his two wingers, Matt Phillips and Chris Brunt, defending as auxiliary full-backs. That stopped Chelsea’s wing-backs from overlapping and all of a sudden Conte’s side had some work to do.
Chelsea created almost nothing in the first half despite dominating possession and the best chances, in fact, fell to West Brom on the break.
Brunt whipped a 30-yard shot just wide of the far post and Salomon Rondon dragged a shot off target after beating David Luiz down the left.
The way in which Costa bullied Gareth McAuley out of the way for his winning goal on Sunday showed that the Spain international has lost none of his aggression, but he is channelling it in the right direction.
There looked to be little danger when he ran on to a high ball from substitute Cesc Fabregas down to right, but Costa completely overpowered McAuley to cut into the penalty area and shoot past goalkeeper Ben Foster.
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