Manchester City were left with a healthy eight-point lead at the top of the Premier League after second-placed Manchester United suffered a 1-0 loss away to champions Chelsea hours after the leaders saw off Arsenal 3-1 on Sunday.
United manager Jose Mourinho, a former title-winning boss with Chelsea, saw his latest visit to Stamford Bridge end in defeat courtesy of Alvaro Morata's 55th-minute header that ended a run of six games without a goal for the Spain striker.
Victory left Chelsea fourth, nine points off the summit.
It was a much-needed win for Chelsea and under-pressure manager Antonio Conte following their midweek Champions League loss away to Roma.
Conte and Mourinho's already tense relationship showed no signs of improving after the Chelsea boss ignored his United counterpart for the traditional post-match handshake between managers.
"It's not important. You have to have the respect on the pitch not outside the pitch," Conte, who at full-time raced onto the pitch to celebrate with his players, told Sky Sports.
Mourinho, twice sacked by Chelsea despite winning the English title three times, insisted he had done all he could to observe the formalities after his third successive defeat at Stamford Bridge.
"You don't want me to chase him into the middle of the pitch," he said. "He (Conte) doesn't have to wait. There is no problem with it at all."
Turning to the result, Mourinho was in defiant mood.
"We are second - not fifth, sixth or seventh or eight," he said. "We have several teams in a more difficult position than we have."
Earlier, City were impressive against the Gunners, with Kevin De Bruyne firing Pep Guardiola's men into an early lead at the Etihad before Sergio Aguero made it 2-0 from the penalty spot early in the second half.
Alexandre Lacazette pulled a goal back for the Gunners but Gabriel Jesus put City 3-1 up in the 74th minute despite a suspicion of offside, with Arsene Wenger's Arsenal now 12 points behind City.
"The third goal, at 2-1 we are in the game and he (referee Michael Oliver) gives a clear offside goal. And, of course, that kills the game for us," said Wenger.
However, City counterpart Guardiola had no truck with suggestions his side had been fortunate to win.
"We won in the best way and we deserved by far the victory," said Guardiola after City backed up their midweek Champions League win away to Napoli.
Injury-hit Tottenham Hotspur, fresh from a superb 3-1 Champions League win over holders Real Madrid, remained level on points with second-placed United thanks to a 1-0 win over bottom-of-the-table Crystal Palace.
Sunday's match at Wembley was deadlocked until the 64th minute when South Korea's Son-Heung Min let fly from 20 yards out.
Spurs were also indebted to their third-choice goalkeeper, Paulo Gazzaniga who marked his debut for the north London club with several fine saves after injuries sidelined both Hugo Lloris and Michel Vorm.
"We knew it would be a massive challenge for us to be ready again and fresh (after beating Real)," said Spurs manager Mauricio Pochettino. "The result was fantastic even if it wasn't our best performance."
Elsewhere, Everton came from 2-0 down to win 3-2 at home to Watford, a result that gave caretaker Toffees boss David Unsworth a first win in charge and bolstered his hopes of taking over full-time at Goodison Park.
Goals either side of half-time from Richarlison and Christian Kabasele put Watford on course for all three points before the Merseysiders pulled one back through Oumar Niasse.
Dominic Calvert-Lewin made it 2-2 when the 20-year-old rising star headed in a Leighton Baines corner.
And Baines himself completed the comeback with a penalty in the last-minute of normal time after Hornets defender Jose Holebas slipped in his own box and inadvertently brought down Aaron Lennon.
Former Everton player Tom Cleverley could have rescued a point for Watford but he missed a penalty in the ninth minute of stoppage time caused by the treatment Hornets goalkeeper Heurelho Gomes needed for an earlier and accidental clash of heads with Kabasele before leaving the field.
(Morata 55) Manchester United 0
(Niasse 67, Calvert-Lewin 74, Baines 90-pen) Watford 2
(Richarlison 46, Kabasele 64)
Manchester City 3
(De Bruyne 19, Aguero 50-pen, Jesus 74) Arsenal 1
(Son 64) Crystal Palace 0