A late strike from Diego Costa has taken Chelsea to the top of the Premier League table with a 1-0 win over West Bromwich Albion.
Antonio Conte's side were frustrated by the visitors for much of the contest in West London but Costa's outstanding individual effort won the game for the Blues, who go three points clear of Arsenal.
It also marks a ninth successive victory for the Blues, who have won each of their matches in England's top flight since October 1.
It soon became clear that West Brom were set up to frustrate the home side - who had not failed to win since the end of September - and the strategy of the West Midlands outfit was effective for the opening 45 minutes
While the Blues were creating nothing going forward, West Brom threatened through Chris Brunt, who lashed a venomous effort marginally wide of the far post from 20 yards.
Six minutes later, West Brom had another opportunity as Salomon Rondon dispossessed David Luiz before driving towards goal, but his shot across goal just missed the far post.
Chelsea needed a response and they almost took the lead in fortuitous circumstances when N'Golo Kante's shot was diverted towards goal by Pedro, but the ball missed the corner with Ben Foster beaten.
Towards the end of the first half, Eden Hazard fired over from inside the penalty area and David Luiz saw a free kick comfortably saved by Foster, but that was as good as it got for Conte's team as the teams went into half time on level terms.
After the restart, several bookings in quick succession resulted in the flow of the game being interrupted, with Chelsea's best opening coming from a free kick from Luiz which was tipped wide by Foster.
Chances continued to be few and far between with Nemanja Matic sending a long-range strike well wide of Foster's goal, but there was nothing which Foster could do to prevent Costa giving Chelsea the lead.
Gareth McAuley appeared to be in control of the ball on the touchline but he was dispossessed by Costa, who ran into the penalty area before driving the ball into the top corner from an acute angle.
Tony Pulis wasted no time in making three substitutions as he put more emphasis on attack, but heading into the closing stages they were unable to create anything as Chelsea looked threatening on the break through Willian and Costa.
The second goal never arrived but with West Brom having to defend during four minutes of added-on time, it mattered little as Chelsea registered another three points to remain clear of the chasing pack.