Bernardo Silva and Leroy Sane struck to hand Manchester City a 2-0 win and bragging rights over rivals Manchester United as they edge closer to a second straight Premier League title.
The two wingers struck within 12 minutes to strike a hammer blow to United's top four hopes and send City a point clear of Liverpool with three games remaining.
Ole Gunnar Solskjaer made five changes from the 4-0 defeat at Everton, including dropping Nemanja Matic and Romelu Lukaku to the bench, and giving starts to Andreas Pereira and Matteo Darmian.
It was a message from the Norwegian that he simply demanded better from his players and would not accept a repeat performance.
With some help from the deafening noise inside Old Trafford, Solskjaer got the reaction he was looking for as his United side went toe-to-toe with their arch rivals.
After a scrappy exchange between the two rivals, there were chances are both ends within the space of a minute.
Bernardo Silva powered a left-footed strike which, while at a decent height for David De Gea, still had to be kept out. And on the break, United went close after Jesse Lingard slid in Marcus Rashford but Ederson came flying off his line with a brilliant challenge to smother the ball.
Raheem Sterling then came close to finding the opener, dancing around three United defenders in the area before scuffing his shot goalwards, but De Gea was equal to it.
That's the closest either side came to breaking the deadlock after a much improved defensive display from United, but after the interval, City came alive.
Just five minutes into the second half, City were dealt a blow when Fernandinho was forced off with a knock. On came Leroy Sane in his place, with Bernardo Silva switching to a deeper role, and it was this tactical switch which proved to be the game-changing moment.
The Portuguese took on Luke Shaw and as he dived inside, he hit a low effort through the legs of the left-back. De Gea was unsighted and soon found himself picking the ball out of the net.
It was the crucial breakthrough that City had been threatening and just 12 minutes later, they were heading towards a vital victory. United were torn open at the back by David Silva and Sane, in acres of space, was invited to shoot by Matteo Darmian. It was powerful but straight at De Gea, and somehow the Spaniard diverted it into his net with his feet.
City controlled possession as they looked to kill the game and despite a flurry of attacking substitutions from Solskjaer, sending on Alexis Sanchez and Lukaku, City held on all too comfortably to take a huge step towards retaining their title.
Relive Man Utd vs Man City LIVE with Standard Sport!
Can't see the blog? Click here for the desktop version.
Manchester derby line-ups
Man Utd XI: de Gea, Darmian, Young, Smalling, Lindelof, Shaw, Andreas Pereira, Fred, Pogba, Lingard, Rashford
Subs: Sanchez, Mata, Lukaku, Martial, Dalot, Romero, Matic
Man City XI: Ederson, Walker, Kompany, Laporte, Zinchenko, Gundogan, Fernandinho, Silva, Bernardo, Aguero, Sterling
Subs: Danilo, Sane, Mahrez, Otamendi, Gabriel Jesus, Foden, Muric
Referee: Andre Marriner
