Erling Haaland scored twice as Manchester City inflicted more pain on Manchester United with a 3-0 win at Old Trafford to close within two points of Premier League leaders Tottenham.
Haaland slotted home from the penalty spot and headed in a second just after half-time before setting up Phil Foden for City's third.
City began the match outside the top four after an indifferent start to their title defence.
But Pep Guardiola's men remain the favourites for an unprecedented fourth consecutive English top-flight title and showed they are a class apart from their local rivals as they moved up to third.
A fifth defeat in 10 league games this season leaves United down in eighth, 11 points off the top.
"Always it is special for us to win here at Old Trafford," said Guardiola.
"It looks easy but it is not. (We have) a lot of respect for United. We were at our best, especially in the second half."
United great Bobby Charlton was again remembered before kick-off as legends from both clubs that played with and against the 1966 World Cup winner were welcomed onto the pitch before a minute's applause.
But hostilities were restored once the action got underway.
After a miserable start to the season, United had won their previous three games but in unconvincing fashion against Brentford, Sheffield United and FC Copenhagen.
This was the real test of any renaissance by Erik ten Hag's men and they were found wanting despite City taking 45 minutes to hit their stride.
- Controversial penalty -
However, Ten Hag claimed it was the controversial award of a penalty midway through the first half that changed the course of the game.
"The first half we played very good, we defended very well. We had good breaks, good opportunities but we could have taken more benefit. Then the penalty changes the game."
Andre Onana saved a penalty with the last kick of the game to secure a vital Champions League win over Copenhagen in midweek that could prove the turning point in his United career after a difficult start.
However, the Cameroonian could not repeat his heroics from the spot when VAR intervened to award City their first penalty at Old Trafford since 1992.
Rodri was clearly hauled back by Rasmus Hojlund, but United will complain that similar incidents often go unpunished for jostling inside the box.
Haaland has attracted some criticism of late for not meeting his usually sky-high standards in front of goal.
But the Norwegian now has 11 in 10 Premier League games this season and sent Onana the wrong way from the spot.
Guardiola was growing visibly frustrated as his side's uncharacteristically poor passing handed United chances to counter-attack as Hojlund and Scott McTominay wasted big chances to equalise.
But the visitors would still have led 2-0 by the break but for a remarkable stop from Onana to turn Haaland's powerful header away.
United did not heed that warning as City did double their lead four minutes into the second half with a carbon copy move.
Bernardo Silva was played in down the left and his cross was this time met by a more cushioned header from Haaland beyond Onana.
City then took complete control and only another fine save from Onana denied Haaland his second Manchester derby hat-trick when clean through.
But City's number nine unselfishly squared with his next chance to claim the match ball, teeing up Foden for a simple tap-in after Onana parried Rodri's initial effort.
The third goal was the cue for thousands of United fans to head for the exits, but not before many had showed their displeasure with Ten Hag's decision to take off Hojlund.
After an impressive first season in charge, the pressure is growing on the Dutch coach to turn around a sinking ship.
kca/mw
