Chelsea moved back to the top of the Premier League and made it nine successive league wins as Diego Costa scored the winner against a stubborn West Brom at Stamford Bridge.

The Spain striker took advantage of a mistake by a hesitant Gareth McAuley in the 76th minute to rob the defender of possession and curl a brilliant left-foot shot past Ben Foster.
West Brom had looked like earning a point after restricting the Blues to just one other shot on target, a 30-yard David Luiz free-kick.
Chelsea also came close through an N'Golo Kante shot that deflected off Pedro and rolled just wide of the post.
The Baggies had early chances through a Chris Brunt shot that fizzed wide and Salomon Rondon shooting across goal.
Chelsea move three points ahead of Arsenal while West Brom stay ninth.
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Gareth McAuley had the opportunity to clear before Costa forced him off the ball

Chelsea had scored 22 in their previous eight league victories but looked likely falling victim to a defensive masterclass from Tony Pulis' side until Costa struck.
The Blues had been frustrated by West Brom's compact defence, which hurried and hassled them from the start and pressed high up the pitch, restricting them to speculative shots from long range until McAuley's error.
The 37-year-old Northern Irishman, who had been booked, had plenty of time to clear a hopeful Cesc Fabregas pass down the line but delayed fatally, allowing Costa to force him off the ball and run inside.
It was the 28-year-old's 12th league goal of the season, matching last season's total.