Alvaro Morata's 55th-minute header sealed a 1-0 win for Chelsea over Manchester United, who fell eight points behind league leaders Manchester City.
Morata, who revealed he had an offer to join United before signing for Chelsea this summer, headed home Cesar Azpilicueta's cross to ease the pressure on Antonio Conte.
With Manchester City beating Arsenal 3-1 earlier on Super Sunday, the title race has already taken a big swing to the blue side of Manchester but Chelsea closed to within nine points with this deserved victory.
The result means Jose Mourinho has not won any of his last 11 Premier League away games at the 'big six' with his teams failing to score in nine of the last 10 matches.
Mourinho's team unexpectedly pressed high early on, with their full-backs playing like wingers at times.
This resulted in an end-to-end game played at a good tempo. Phil Jones thumped a left-wing cross into his own net but was deemed to have been fouled by Morata while Marcus Rashford looped a header over the crossbar when well placed.
Tiemoue Bakayoko then sliced wide with the goal gaping and Andreas Christensen headed over from seven yards out following a wonderful Cesc Fabregas corner.
Their next headed chance would not be wasted. With 55 minutes gone, Azpilicueta found space down the right and planted a sensational ball into Morata, who thumped a header into the top corner. It was the fifth time this season Azpilicueta had supplied an assist for the Chelsea striker.
Chelsea looked the more likely to grab the second goal with Bakayoko firing wide when clean through on goal before Eden Hazard forced a smart save from David de Gea.
With the clock running down, the withdrawal of Fabregas seemed to inspire United and substitute Marouane Fellaini was denied by a flying Thibaut Courtois save.
That proved to be the last chance as Manchester City head into the international break firmly in control of the Premier League.
Man of the match - Cesc Fabregas
Fabregas was allowed plenty of space by the opposition midfield and he revelled in it, creating six goalscoring opportunities in the match - no other Chelsea player provided more than one. His link-up play with Hazard and Morata, especially in the second-half, provided a platform for Chelsea to pin United back. When he was taken off with 12 minutes to go, United breathed a huge sigh of relief.
Opta stats
- The Blues have lost just one of their last 16 Premier League home matches against Man Utd, winning 10 and drawing five.
- Morata has had a hand in 10 goals in his opening 10 Premier League games for Chelsea (7 goals, 3 assists) - only Diego Costa was involved in more in his first 10 for the club (11).
- Morata has scored 10 headed goals in league competition since the start of last season - no player in the big five European leagues has scored more (level with Andrea Bellotti).
- After recording 20 shots on target and scoring seven goals in their first three away league games this season, the Red Devils have managed just six in their last three, scoring once.
- There are now eight points separating Man Utd in second and Man City in first - the biggest ever such gap after both the top two have played 11 games in Premier League history.
The managers
Jose Mourinho: "The game was controlled by us and the game was controlled by them. We had chances and they had chances. We had a go, we tried to change the direction of our game. We created chances to equalise but we couldn't. There is still a lot of play. I hope, feel, think and wish that in the busy festive period and new year we are going to be at maximum strength with Paul Pogba, Ibrahimovic and Marcos Rojo back."
Antonio Conte: "I was very happy because we beat a strong team like Manchester United. To have this type of performance and to see this spirit, for sure I'm pleased. We have to continue and to understand if there is this spirit, this enthusiasm, this passion, we can fight for something important."
What's next?
After the international break, Chelsea travel to West Brom - the scene of last season's title triumph on November 18, while Manchester United host Newcastle later that day.