The hosts came into the fixture on a good run of form, having gone nine games unbeaten in all competitions but Guardiola had a very good recor1d at Old Trafford and had not lost a league match at the Theater of Dreams since arriving in England.
He fielded an unfamiliar backline, while injury also ruled out star man Kevin De Bruyne but even in his absence, Manchester City dominated the early proceedings, with the hosts forced to sit back and absorb the pressure.
Manchester United, however, had the best chances of the early periods and went ahead through Anthony Martial from a well-worked freekick in the 30th minute.
Smart tactical decisions by Ole Gunnar Solskjaer guaranteed that his side saw out the match and Scott McTominay struck the decisive blow late into injury time to ensure that the Norwegian became only the second manager after Nuno Espirito to win Guardiola home and away in the same league campaign and equalled Jurgen Klopp's record of defeating the Catalan three times in a single season.
The win gave Manchester United an invaluable three points in their quest for a top four finish and here, we shall be highlighting five players who shone for the Red Devils in their derby day delight.
5. Harry Maguire
Manchester United have kept four consecutive clean sheets at Old Trafford and seven in their last nine games in all competitions and a large reason for their improved defensive solidity has been the performance of their skipper.
The former Leicester man was once more a defensive rock at the back and led by example with his tireless contributions and marshalling of the defence in the face of sustained pressure by the City attackers.
Bar a mistimed header in the first half, Maguire did not put another foot wrong all match and was up to the task of keeping Sergio Aguero quiet.
The 27-year-old made six clearances and two interceptions, limiting City to just one shot in the first half (their lowest since October 2018) and he continued his job of slowly winning over critics who scoffed at the word record fee paid for him in the summer.
4. Nemanja Matic
Nemanja Matic has been reborn in recent weeks and his improved form has led to a contract extension that would see him spend another year at Old Trafford.
He responded to the show of faith by turning in another fine display at the heart of midfield alongside Fred and was very efficient in his role of breaking up the City attacks, while he also contributed to Manchester United's forays forward.
The Serbian international made three interceptions and three clearances and also contributed a key pass in what was a flashback to when he was one of the best holding midfielders in the world.
3. Aaron-Wan Bissaka
Aaron-Wan Bissaka was by far the best defender on the field and he played a key role in keeping Raheem Sterling quiet throughout the match, forcing City to focus most of their attacks on the other flank.
The 22-year-old has made a name for himself over the last two years with his defensive solidity and he brought his A-game to the fore against the Cityzens, with his eight tackles more than anyone else managed on the field, while he also contributed two interceptions and two tackles to his side's defensive cause.
A criticism of his game has been his lack of product going forward but Wan-Bissaka showed a willingness to surge beyond the midfield line, with a particular run of play where he showed great skill to pull off a flip-flap and skip between three City players indicative of his growing confidence.
2. Bruno Fernandes
Since making his Premier League bow for Manchester United in February, nobody has been involved in more goals than Bruno Fernandes (two goals three assists) and he was once more at the heart of everything good about his side's attacking play.
The Portuguese international made three key passes in the match, with one of those being an ingenious flick of the ball from a freekick on the edge of the area that Martial finished on the volley and even though there was a lot of debate over the veracity of the freekick, it takes nothing away from the brilliance of Fernandes' execution.
The former Sporting man was an ever-present on the occasions that Manchester United ventured and he dictated their play with his forward-moving passes, while he also put in a defensive shift, with three interceptions and one clearance made at the other end.
He was substituted for Odion Ighalo in the 87th minute and the rapturous ovation he got from the United fans was just appreciation for another sublime performance from the middle of the park.
1. Anthony Martial
Anthony Martial started as the focal point of Manchester United's attack and he continued his recent good form by opening the scoring in a tense Manchester derby.
The 24-year-old had earlier shown flashes of his exasperating behaviour, shooting tamely at Ederson when played in through on goal but he soon made amends for that with a well-taken strike in the 30th minute.
In the aftermath of the win over Watford, Bruno Fernandes had joked that Martial should have finished first-time on his assist rather than produce a piece of individual brilliance and the Frenchman duly obliged this time around, with their two-touch move seemingly off the training ground, although Ederson should have done much better.
The goal means that Martial has scored three in his last four, while he also became the first man since the great Eric Cantona to score against Manchester City in three consecutive starts and if he continues in this form, Manchester United would fancy their chances of pipping Chelsea to the top four.