Chelsea secured their 10th consecutive Premier League victory with a 1-0 win over Sunderland on Wednesday to send them six points clear at the top of the table.
Cesc Fabregas' first league goal of the season put the Blues in front (40) at the Stadium of Light and they had chances to make the game safe through Diego Costa, N'Golo Kante and Willian.
But they were nearly punished in stoppage time when Thibaut Courtois denied Patrick van Aanholt with a stunning stop, preserving his clean sheet and extending Chelsea's winning run.
Arsenal's defeat to Everton on Tuesday opened the door for Antonio Conte's side and they took full advantage, moving six points clear of second place and guaranteeing top spot over Christmas.
That's a good omen for the Blues considering six of the last seven teams to top the table over Christmas have gone on to win the title.
Sunderland remain bottom, with Watford set to visit the Stadium of Light next on Saturday.
Chelsea, without the injured Eden Hazard, struggled to make inroads in the early stages and Sunderland had the first chance when Adnan Januzaj sliced over.
But the hosts gradually retreated as the half progressed and a moment of quality from Fabregas broke the deadlock five minutes before the break.
Willian and Fabregas had been recalled by Conte in place of Hazard and Nemanja Matic, and the pair combined before the Spaniard swept past Jordan Pickford to put the visitors ahead.
Willian went close to doubling their lead on the stroke of half-time, but his free-kick landed on the roof of Pickford's net.
Januzaj, who was bright on the flanks for the home side, forced Courtois into a smart stop shortly after the interval but Chelsea swiftly regained control.
They should have been out of sight as Willian's deflected strike hit the crossbar and Pickford denied Costa and Kante, while Victor Moses and Fabregas flashed efforts wide.
But they failed to put Sunderland away and the relegation battlers had two late chances to snatch a point.
Jason Denayer headed straight at Courtois from van Aanholt's cross, before the Dutch defender forced the save of the match from Chelsea's Belgian goalkeeper.
Van Aanholt smashed a fine strike towards the top corner after working space on the edge of the box, but Courtois sprung to his right to tip wide.
The Blues travel to Crystal Palace next in the Premier League, looking to put further pressure on their title rivals with an 11th straight league win.
Player ratings
Sunderland: Pickford (7), Jones (7), Van Aanholt (7), Djilobodji (6), Kone (6), O'Shea (6), Denayer (6), Kirchhoff (5), Januzaj (7), Borini (6), Defoe (6)
Subs used: Love (6), Larsson (6), Khazri (6)
Chelsea: Courtois (8), Azpilicueta (6), David Luiz (6), Cahill (6), Moses (8), Kante (7), Fabregas (9), Alonso (7), Willian (8), Diego Costa (7), Pedro (7)
Subs used: Ivanovic (6), Chalobah (6), Matic (6)
Man of the match: Cesc Fabregas