However United owed much of their success today from the hapless but usually dependable Ederson.
Story of the match
Since Guardiola's arrival, most Manchester Derbies have been rather repetitive with City dominating possession and United looking to counter-attack. Whilst this approach in these matches have ultimately ended in victory for Pep's side, this wasn't the case with today being a prime example of the typical encounters between the fierce neighbours.
City unsurprisingly dominated proceedings forcing a few early corners and giving David De Gea a few things to clean up, but none of City's early dominance led to any serious chances aside from one effort by Raheem Sterling in the 11th minute.
The move initially occurred because of Sergio Aguero's persecution of Luke Shaw which ultimately led to the Argentine winning the ball then proceeding to cutting the ball back to Phil Foden who picked a lovely chipped pass out to the left wing to Raheem Sterling who typically cut inside and forced a good save by the Spanish goalkeeper who had to dive low to his left.
A particularly slow first half exploded into life after half an hour. Bruno Fernandes making his first derby appearance cleverly won a free-kick which he took, the awarding of the set-piece may have been soft but after that, it was pure genius play from the Portuguese man.
An ingenious chip over the top was read by Anthony Martial who capitalised on sloppy play by his marker, the Frenchman spun, connected well with the pass and unleashed a right-footed half volley into the left-hand corner of the goal.
Ederson who has been a salvation for City in his tenure at the club had a day to forget. Whilst Martial's shot was struck cleanly it did not have much venom behind it, Ederson anticipated the shot and even got a hand to the ball but not a strong enough hand and the ball eventually nestled into the net. Ole's game plan was working once again and United went into the lead.
Despite City's dominance on the ball they failed to create much in the first half and were fortunate not to fall even further behind as Fred had a strong penalty appeal turned down following a rash challenge by Nicolas Otamendi by Mike Dean and the VAR officials. The referee, despite the aid of the technology available to him initially awarded the Brazilian a yellow card and did not overturn his incorrect call.
As if Ederson's day could not get any worse, it very nearly did after a routine back pass from Joao Cancelo was misread by the keeper who allowed the ball to slip under his foot almost allowing Martial to slide in for his second of the match.
City continued to probe for the equaliser without pressing too much and Foden came close just before the hour mark with a fine strike 25 yards out forcing a good save from De Gea who tipped his shot over the bar.
As the clock ticked on Pep's side started to apply the squeeze, Sterling was inches away from meeting Riyad Mahrez's right-wing cross, substitute Gabriel Jesus picked up the loose ball, cut inside and forced another good save from De Gea.
As City attempted to throw the proverbial 'kitchen sink' at United's defence, the blues were always suspect to the counter-attack and lo and behold they were caught with a sucker punch from the Scotsman Scott McTominay seconds from the full-time whistle.
To well and truly compound Ederson's horrific day a routine throw out to full-back Benjamin Mendy was too powerful on the greasy Old Trafford surface due to the torrential rain, the defender had no chance of receiving his keeper's pass but McTominay did.
40 yards out without even taking a touch the Scot arguably produced the finest moment in his career thus far and smoothly slotted his shot into an empty net with Ederson still recovering from his failed throw out.
City's miserable day was compounded as Manchester United secured their first double since the 2009/10 Premier League season.
Takeaways from the match
A bittersweet day for Manchester United who are looking good for a Champions League place next season
Manchester United will take a lot of heart and pride from this performance as they secured their third victory of the season against their neighbours as they moved ever closer to a top-five finish and ultimately UEFA Champions League football following their absence in this year's competition.
However, today's victory meant that their fiercest and most hated rival Liverpool are now two wins away from securing their first-ever Premier League title and their first for 30 years.
Much to ponder for Pep in another harrowing loss against their rivals
Pep Guardiola may finally be alarmed over the type of loss they suffered today due to the similarities of defeats in two of the other three previous meetings. Without the influential Kevin De Bruyne in central midfield, City looked rather ordinary and did not look like creating much at all today.
Whilst Phil Foden will be a wonderful player in the future it is essential that Pep surrounds him with players of similar ilk, unfortunately, Rodri and Gundogan were not able to provide the young Englishman with much support today.
Up next for both
Its a quick turn around for both as Manchester United are in action in the UEFA Europa League with a round of 16 first leg match against LASK in Austria.