- Costa fires home only goal (76)
- Albion's four-match unbeaten run ends
- Dawson suspended for Swansea on Wed
- Attendance: 41,622
- Albion Star Man: Claudio Yacob
ALBION fell to a second-half finish from Diego Costa as Premier League leaders Chelsea finally broke their resistance.
The Baggies proved a match for their high-flying hosts, who went into the Sunday lunchtime encounter on the back of eight successive victories.
Chelsea dominated possession in west London but failed to seriously trouble Ben Foster as Tony Pulis' well-organised side proved difficult to break down.
Yet in the 76th minute of the encounter, Costa won possession down Albion's left and broke into the penalty area before firing high into the top corner, much to the relief of the majority of the 41,622 present.
Defeat ended Albion's four-match unbeaten run but they will be looking to bounce straight back on Wednesday at home to Swansea, against whom Craig Dawson will be suspended having collected his fifth booking of the season.
Albion made a bright start and, after a couple of half-chances, Chris Brunt flashed an effort narrowly wide from distance.
The Baggies were more than holding their own and Salomon Rondon was next to flash a shot across the face of Thibaut Courtois' goal.
Chelsea threatened for the first time just before the half-hour mark as N'Golo Kante's low shot was inadvertently deflected narrowly wide by Pedro, with Foster stranded.
David Luiz's dipping free-kick forced Foster into action yet an intriguing encounter finished goalless at the break.
Foster tipped around another Luiz set-piece after the restart but the Baggies continued to match their hosts.
However, the all-important breakthrough came 14 minutes from time as Costa won the ball in a dangerous area and left Foster with no chance.
Albion: Foster; Dawson, McAuley, Evans, Nyom; Yacob, Fletcher (c); Brunt (Robson-Kanu 84), Morrison (Chadli 78), Phillips (McClean 78); Rondon.
Subs: Palmer; Olsson, Gardner, Galloway.
BOOKED: Brunt (foul, 20), McAuley (foul, 29), Dawson (foul, 51), Yacob (foul, 56)
Chelsea: Courtois; Azpilicueta, Luiz, Cahill (c); Moses (Fabregas 74), Kante, Matic, Alonso; Pedro (Willian 63), Costa, Hazard (Ivanovic 79).
Subs: Begovic, Aina, Chalobah, Batshuayi.
BOOKED: Kante (foul, 48), Matic (foul, 88)
Referee: Mike Dean (Cheshire)