Chelsea chose to rest Oscar and Juan Mata for the game, and their absences showed as West Brom were able to impose themselves on the game. A rare Chelsea chance in the first half resulted in Ryan Bertrand having a shot cleared off the line, but seconds later it was the hosts who put themselves ahead, James Morrison crossing from the left for Shane Long to head home.
Chelsea struggled to penetrate a solid Baggies without their two creators, and Daniel Sturridge had a good opportunity but could only provide a tame shot. West Brom almost doubled their advantage through the lively Shane Long, but the next goal would go to Chelsea, Eden Hazard getting on the end of Cesar Azpilicueta's deep cross to score his first ever headed goal.
The teams had gone off at half-time to a volley of boos after a perceived penalty shout was turned down by the referee for the home side, but it was soon the visitors who had cause for complaint, Claudio Yacob shoving Victor Moses down in the area to make it one injustice each.
Chelsea introduced Mata and Oscar late on to try and force the issue, but could not put West Brom under any real pressure. Daniel Sturridge was the liveliest but his finishing let him down, bursting into the area but being denied by an excellent save from Boaz Myhill when one-on-one. Immediately afterwards, Graham Dorrans almost put gloss on the scoreline after collecting an excellent cross on the breakaway from Shane Long, but his chest control let him down and the ball ran out of play.
The final whistle was met by raucous cheers from the home team and reflected not only a great victory but a hugely accomplished performance from a team that currently looks every bit the fourth-best team in England. Chelsea will hope that today was just an off-day due to the lack of fitness of their attacking midfielders, or they will be firmly the third-best.