Manchester United boss Ole Gunnar Solskjaer hailed his club's best performance of the season after a 2-1 victory at the Etihad put a massive dent in Manchester City's title hopes.
First half goals from Marcus Rashford and Anthony Martial was rich reward for a thrilling counter-attacking style as the visitors put Pep Guardiola's men to the sword with pace and power.
It came just days after United had ended ex-boss Jose Mourinho's winning start at Tottenham with the same winning scoreline at Old Trafford.
Not bad for a manager supposedly under pressure who was forced to deny reports that two defeats would have spelt the end of his tenure.
For Guardiola it was a painful watch. City huffed and puffed but lacked bite going forward and were too easily exposed at the rear.
A header from substitute Nicolas Otamendi with five minutes remaining gave some hope for Pep Guardiola's side but it was too little, too late.
Bookies were offering long odds of 7-1 against United in this contest - such has been the contrasting fortunes in recent seasons - but it didn't take United long to make light of their unfancied prospects.
City keeper Ederson had denied Marcus Rashford, Daniel James and Jesse Lingard in the early stages but was powerless to keep out Rashford's penalty after he was brought down by a clumsy challenge from Bernardo in the box. Referee Anthony Taylor originally waved away penalty claims but a VAR check forced him to overturn his decision.
The England striker then hit the bar before Martial squeezed home a second at the near post before the half-hour after being picked out by James.
Although it was the end of United's scoring, they continued to look dangerous on the break and defended stoically as City began to dominate in the second-half.
Bodies were put on the line and Harry Maguire organised the rearguard effectively as wave of City pressure was repelled.
"When you consider who we are playing and where we are playing," said Solskjaer when asked if that was the best we've seen from his side this term.
"We have had to reshape the squad and change the culture and change the way we want to play.
"When you prepare for these games to watch so many [past matches] - it's not nice to see that City are so much better."
He added: "We will remember this one. We look so dangerous when we get the ball and go forward against arguably the best team in the world."
United now trail City by eight points but have reduced the arrears on fourth-placed Chelsea to a more manageable five points as they target the Champions League places.
However, for City, defeat now leaves them 14 points off leaders Liverpool and no club in history has ever made up such a gap to claim the title.
City have dropped eight points in their last five outings and Guardiola's tally of 32 points is the lowest of his managerial career after 16 fixtures.
He said: "They are so quick and sometimes when you lose the ball it is more difficult. We tried, we got to the last third many, many times and they can run. Maybe a bit more than usual."
The Spaniard refused to concede the title, and added: "We have to try to continue. There are many things to play for. It's difficult because the opponents are on an incredible run winning 15 out of 16 games."
The match was overshadowed by claims of racism directed towards some of the United players, including Fred, in the second-half.
By Russell Stoddart
Images: Getty Images