This was one of Manchester United’s best chances of beating their neighbours when Guardiola has been in charge, with the Catalan keen to see a response from his team after their dismal Carabao Cup loss to Southampton in midweek.
The game settled into a decent pace from kick-off. Bernando Silva’s loose pass allowed the hosts to mount an attack, but compatriot Fernandes dragged his effort wide.
Fred was doing a sterling job of sticking to Kevin De Bruyne, and the Belgian, who hadn’t got a league goal or assist since 29 October before this match, was struggling to influence proceedings early on.
Erling Haaland’s first shot in anger from the edge of the area was blocked on 24 minutes, before Ederson had a heart-in-mouth moment as he charged out to meet Rashford and the striker rounded the Brazilian, only for Manuel Akanji to intervene on the line.
Rashford was then put through again, but Ederson smothered effectively as he bore down on goal. However, the England international was soon in pain after appearing to pull up injured but soldiered on until the break.
Rashford was able to continue at the start of the second period, but Martial was instead taken off, Antony taking the Frenchman’s place.
On 54 minutes, De Bruyne was able to stretch his legs and hang up a cross for Silva, but the Portugal international’s header back across goal was cut out vitally by Raphael Varane.
The creator supreme couldn’t be tied down though, and another hanging ball into the danger area was powered home by Grealish.
Erik ten Hag threw on 18-year-old Alejandro Garnacho in an attempt to turn the tide, and United equalised 12 minutes from the end of normal time when Casemiro’s inch-perfect through-ball was swept home by Fernandes.
The effort was initially ruled out because it was thought that Rashford, in an offside position, had touched the ball. However, after referee Stuart Attwell spoke to assistant Darren Cann, the goal was given.
"Scoring a goal and winning the game, that's always the aim. This game is a little special," Rashford told BT Sport.
"It's a change of dynamics. I've said many times but options off the bench even when we've had injures, players out of position, everyone is putting a shift in.
"Anything is possible. We’re very pleased to come back and win."
And United stunningly completed the comeback when Fernandes instigated a breakaway with a superb reverse pass to Garnacho, who scampered forward and had a cross blocked by Akanji, but the 18-year-old regained possession and spun Nathan Ake to produce a fizzing cross that Rashford tucked between Ederson’s legs to send the home fans berserk.
That crushing defeat means City must hope that Arsenal fall to defeat in Sunday’s north London derby. A victory for the Gunners however would put Mikel Arteta’s men eight points clear.
"The game was really good," coach Pep Guardiola told BT Sport. "We played good. They are incredible in transitions. Congratulations to the team. I'm proud to come here and play with this personality. They punished us in transitions."
Flashscore Man of the Match: Bruno Fernandes (Manchester United)
