A first-half strike from Cesc Fabregas has earned Chelsea a 1-0 victory over Sunderland at the Stadium of Light.
The goal from the Spaniard also gives the Blues their 10th successive win in the Premier League, and they now sit six points clear at the top of the standings.
Chelsea began the game on the front foot with Marcos Alonso blazing a speculative effort over the crossbar, but that was as good as it got for the West London outfit in a drab opening half-hour.
The visitors were dictating the pace of the play but as they created very little in the final third, Sunderland carved out the best opportunity through Adnan Januzaj, who saw a curling effort deflected wide of the far post.
The Premier League's top goalscorer Diego Costa endured one of his quietest 45 minutes of the season with his only attempt being a miscued volley which went nearer the corner flag than Jordan Pickford's goal.
However, towards the end of the half, Chelsea improved and moments after David Luiz had hit the target with a 35-yard free kick, the Blues took the lead as Fabregas found the back of the net after being set up by Willian.
Sunderland needed a considerable improvement after the restart and they should have equalised two minutes into the second half when Jermain Defoe set up Januzaj, but the Manchester United loanee could only fire too close to Thibaut Courtois.
Moments later, Chelsea were unfortunate not to add a second when Victor Moses fired a deflected effort just wide of the far post, but it sparked a spell of Blues dominance as they pressed for a second.
Firstly, Willian glided past two players before hitting the crossbar with a deflected shot, while Costa forced a solid intervention out of Pickford after breaking into the penalty area.
Moses then cut inside before sending a low shot just past the post, moments before Willian did the same on the left-hand side of the area and fired wide of the far corner.
Even N'Golo Kante was interested in a second Chelsea goal as he saw a shot smothered by Pickford before up the other end, Defoe volleyed wide after beating Luiz.
Chelsea looked comfortable heading into three minutes of added-on time but Sunderland squandered two chances to earn a share of the spoils, the first coming when Jason Denayer headed straight at Courtois.
In the final seconds, Patrick van Aanholt fired a volley towards the bottom corner but Courtois was there with the diving save, just as the Dutchman thought he had secured a draw against his former club and lifted his team off the bottom of the table.
