The self-proclaimed ‘Special One' surprised the world by naming an attacking XI with Anthony Martial, Juan Mata and Marcus Rashford all on from the off, while Maurizio Sarri had a surprise of his own up his sleeve as he named Álvaro Morata in his team ahead of Olivier Giroud.
The home side started the match on the front foot but it was the Red Devils who had the first real opportunity of the match. Romelu Lukaku managed to find space in the penalty area but he couldn't make the most of the chance and his header floated wide.
Chelsea looked dangerous in open play but the opener arrived via a set piece. Willian's corner kick was emphatically powered home by Antonio Rüdiger. The Germany international left Paul Pogba, tasked with marking him, in his wake and nodded the 2016/17 champions into the lead.
Mourinho's men failed to have a shot on target in the opening 45 minutes and had to wait until the 54th minute to trouble Kepa between the Chelsea sticks. The Spaniard repelled Mata's effort but the home team wouldn't clear the danger. The ball found its way to Martial and the Frenchman fired home the equaliser.
Chelsea pressed on looking to regain the lead and this left them exposed to the counter. A quick break down the United right resulted in Rashford feeding the ball to Martial on the left. The former Monaco man cut inside onto his favoured right foot and bend the ball past the outstretched Kepa.
United had turned it around for the second successive Premier League match. Mourinho, despite reports suggesting otherwise, still has the support of the dressing room.
It appeared as though Mourinho had committed a smash and grab on his former club but there was one last twist in the tale. A Chelsea free-kick in the 95th minute was only half cleared. The ball was clipped back into the area and David Luiz's thunderous header hit the post. Rüdiger nodded it goalwards only to be thwarted by David de Gea but the ball bobbled out to Ross Barkley who made no mistake.
Here are five things we learned as Chelsea extended their unbeaten streak.
Mata is a classier Herrera
The United No.8 is one of the best playmakers in the Premier League. But Mourinho being Mourinho saw something many others didn't. The Portuguese tactician deployed Mata in a man-marking role to keep close tabs on Jorginho.
Yes, Mata, the man with the ability to thread the ball through the eye of a needle, was given a job usually associated with a defensive midfielder. One with the discipline to know when to push on and when not to, the intelligence to know what space to cover, and the energy to get around the pitch.
But in a weird way it worked, so credit to Mourinho. Mata was always buzzing around Jorginho in Chelsea's defensive third. The idea was a sound one; if the United man managed to dispossess the adopted Italian then he would have the vision and the ability to execute a pass which would allow the away side to hit Chelsea on the break. A tactic discussed in detail in the preview.
There’s a bullseye on Hazard’s back
When you're the best player in the Premier League you're going to be kicked. It comes with the territory and Eden Hazard found that out today. It was clear from the off that Mourinho had instructed his players to make it as uncomfortable as possible for the brilliant Belgian and they took turns fouling him throughout.
Ashley Young and Nemanja Matć had nibbles at him even when on yellow cards. On one hand, it is a cynical way to deal with a player. On the other, it worked. For only the second time this season Hazard failed to score or assist in a match. Furthermore, he completed just two dribbles, way down on the 3.5 he's averaged this term.
Mourinho doing whatever it takes to pick up all three points is nothing new.
Will the real Pogba please stand up
Paul Pogba looks like an £89million player when turning out for France. The same can't be said when he's wearing the red of Manchester United. He swaggers around the middle third for the World Cup winners, pinging passes to team-mates and making rampaging runs through the heart of the opposition's team. A player of supreme confidence
Yet under the watchful eye of Mourinho, he looks stressed. His play can be sloppy. He switches off and his tactical discipline is questionable. The pressure he puts on himself is having an impact on his performance.
He was at fault for the opener. Rüdiger easily escaped his close attention and scored what was possibly the easiest goal of his career. Pogba's frustration afterwards was evident. But he didn't react like a world class player does.
There was no desire on his part to take the game by the scruff of the neck and make amends for the mistake. Instead, it was almost as though he appeared to sulk for the remainder of the first half. In the entirety of the game, he attempted just 38 passes. Fewer than Matić and Victor Lindelöf.
Pogba is no 25, consistency needs to be part of his game. Which side of the fence is he going to settle on?
Morata is in last chance saloon
The Spain international was given the nod ahead of Giroud to lead the line. The 25-year-old was in good form heading into the match having scored two goals in his last two outings for the Blues. He should've been full of confidence but it quickly became apparent that he's still a long way away from the Morata who impressed regularly for Juventus and Real Madrid.
Barring one good interchange with Hazard, Morata was on the peripheral at best. His hold up play was erratic with the ball bouncing off of him at times while his decision making was lacking. At times he was looking for a foul when Chelsea had the opportunity to break had he got his head up and look at his options.
With Sarri's men genuine title contenders this term they can't afford to carry passengers. Morata, as is, is a passenger. Unless he turns it around it wouldn't be a surprise to see him shipped out in January with Chelsea bringing in a more reliable forward.
Martial proves his worth
Martial is a world-class talent but like so many other United players under Mourinho, he just isn't consistent enough. However, unlike the rest, he isn't given the opportunities with the manager preferring Alexis Sánchez and Marcus Rashford out wide.
But after watching him today against Chelsea, and seeing how genuinely ruthless he is when he's got half a chance, you have to wonder why Mourinho is so reluctant to unleash him against Premier League defenders.
He's a genuine threat. His pace, unpredictability and raw finishing ability make him a nightmare to defend against. United would be better with him in their starting XI in most matches. Can this be the turning point or will he, as reports claim, look to complete a cut-price move away in the summer? It'd be a costly mistake if the latter happens.