Chelsea are heading inro another crisis as they slumped to another defeat at the Hawthorns as the Baggies poached all three points.
Goals from Shane Long and Peter Odemwingie were enough, with Eden Hazard's early second half header the only bright spot in a miserable game for the Londoners in the West Midlands.
This was the corresponding match last season which Chelsea lost, which saw Andre Villas Boas lose his Chelsea job, and, while Roberto Di Matteo is yet to find himself under similar pressure, the poor run of league results are stacking up against the Italian.
Chelsea started off the better side with comfortable possession. Daniel Sturridge tried his luck from 20 yards on five minutes but his weak shot failed to trouble Boaz Myhill in the WBA goal.
The Blues should have gone ahead three minutes later when an incisive run into the penalty area by Victor Moses saw Ryan Bertrand get a shot away which was hacked off the line by Liam Ridgewell, and then a follow-up drive by Eden Hazard saw Jonas Olson appear to block the ball with his hand, but referee Michael Oliver waved play on.
Chelsea were undone with WBA's first attack of the game when Shane Long got his head to a cross from just inside Chelsea's penalty area by Zoltan Gera and powered home from a diving header at Petr Cech's far post to put the home side one up.
A Sturridge snap shot from the edge of the WBA box was the best the Blues could muster as they attempted to pass the Baggies to death.
But Steve Clarke's side were more than happy to soak up this lack of pressure and counter-attack, which they did with vigour on 37 minutes, resulting in what looked like Gary Cahill tangling with Long.
The striker claimed a penalty but Oliver, once again, denied the appeal. As the cliche goes it only takes a minute to change a game and the visitors did just that on 38 minutes.
Belgium midfielder Eden Hazard, wide on the left of WBA's area, clipped the ball high across the area to the awaiting Chelsea fullback, Cesar Azpilicueta. The Spain defender then returned the compliment, and at the far post, Hazard headed the ball towards goal.
The unfortunate Olsson, trying to clear It, could only help it on its way and the Blues were level.
Moses could have put Chelsea ahead in the stroke of half-time, but he blasted a right- footer high and wide of Myhill's goal.
The Blues started the second half as they did the first, in the ascendancy.
Myhill was forced into an excellent block after Sturridge's blaster on 48 minutes.
But also like the first half, Chelsea switched off and two minutes later with the home side's first attack, they retook the lead,
It was the simplest of affairs, a clipped ball, on the right by an unmarked James Morrison and Petr Odemwingie got in front of Bertrand and glanced his header wide of Cech from eight yards out at the near post.
Chelsea boss Roberto Di Matteo had seen enough. On 62 minutes, he decided that Brazil midfielder Oscar and the mercurial talent of Juan Mata was required.
Off came Oriel Romeu and Fernando Torres.
Sturridge, moved up to Torres's central shrinking position, could only just get his head to an through ball by Mata a minute later. Unluckily for him, he could not control it properly and the chance faded away.
Myhill was alive to another through ball by Mata seconds later and was not distracted from a Sturridge lunge for the ball, instead, he cleared it to safety.
With Chelsea,desperately trying to get back into the game, ex-Chelsea coach Clarke assessed that the Blues would be even more exposed on the counter-attack and so replaced Gera and Morrison for Graham Dorrans and Chris Brunt with 20 minutes to go.
Sturridge, who craves a starting place as the central striker did everything right on 77 minutes, racing into yet another Mata through ball. Accelerating past the centre-backs,
Sturridge raced into the WBA penalty area and let fly with a venomous shot. But, not for the first time, Myhill stood in his way and the goalkeeper blocked the goal-bound effort.
Di Matteo's last throw of the die was to bring on Brazil midfielder Ramires for Mikel with 10 minutes remaining to add increased thrust from the middle of the park.
Sturridge, just off the pace needed up front, once again just missed the ball after another inch-perfect pass by Mata bisected the WBA rearguard.
Sturridge really should have levelled the match for the Blues with four minutes remaining. He received a simple pass from Oscar yet managed to screw his shot across goal from close range with Myhill beaten.
Quite why Chelsea continued to pump balls into the penalty area from wide positions, was anybodies guess as the WBA defenders gratefully headed the ball away.
In the dying seconds, Chelsea had a corner. Sturridge passed it to Mata who clipped it into the box. Cech, up from his goal, almost got his left foot to the ball, but the ball was slightly overhit and WBA breathed a sigh of relief.
That was he end of the action. Chelsea now face the daunting task of getting something in Turin against Juventus in the Champions League before facing Manchester City at the Bridge at the weekend. Iw Teams
Chelsea Cech, Azpilicueta, Cahill, David Luiz, Bertrand - Romeu, Mikel - Moses, Hazard, Sturridge - Torres
Subs, Turnbull, Ivanovic, Cole, Ramires,Mata,Oscar, Marin
WBA : Myhill, Olsson, Yacob, Ridgewell, Morrison, Long, Mulumbu, Gera, Odemwingie, Jones, Tamas
Subs, Daniels, Reid, Popov, Rosenberg, Brunt, Dorrans, Fortune.
Referee, Michael Oliver