Perhaps there will be a day in the future when José Mourinho can return to Stamford Bridge without the rancour and acrimony that accompanied this tie. It might, however, be a long time away judging by the sourness that infiltrated another triumphant night for Chelsea and left Mourinho trying desperately to get in the last word. “Judas is No1,” was a nice soundbite from the former Chelsea manager, reflecting on his trophy count in these parts, but only a small victory considering the joys for Antonio Conte.

By the time it was all done Conte’s team were into a semi-final against Tottenham and their supporters were left wondering whether he might emulate Carlo Ancelotti by finishing his first season at the club with the double. N’Golo Kanté had scored in the game’s decisive moment five minutes into the second half and, after that, it was always going to be difficult for Manchester United bearing in mind Ander Herrera had been sent off during what looked suspiciously like a premeditated campaign to target Eden Hazard. Conte was convinced, accusing United of “trying to intimidate” and describing their tactics in this part of the match as “only kicking”.

It was probably no surprise, therefore, there were times when Conte and Mourinho clashed on the touchline like two warring stags. A feud is taking shape and it cannot help Mourinho’s mood that the new guy in town keeps getting the better of them. This was the second time Mourinho has been back to Chelsea and he has lost both times, conceding five goals and not scoring once.

The repercussions for United could involve disciplinary action for the team because of their protests after Herrera’s second yellow card. Marcos Rojo could also be in trouble after a stamp on Hazard and, along the way, there was the hard evidence of how Mourinho’s relationship with the Chelsea supporters has changed. A manager with his trophy collection might have thought he was immune to the kind of vitriolic chants and abuse that could be heard behind his dugout. Mourinho responded by holding up three fingers – one for each league championship – and it is safe to assume this is how it is going to be from now onwards. Diplomatic relations are off.

Did United really target Hazard? It was nothing like as brutal as the time, infamously, when a succession of Sir Alex Ferguson’s players ganged up on José Antonio Reyes during the height of the United-Arsenal rivalry. Yet the referee, Michael Oliver, was sufficiently concerned to hold up play after 35 minutes and bring over United’s captain, Chris Smalling, to make it clear that he would not tolerate any more. Play restarted and Herrera, already booked for a bodycheck on Hazard, evidently did not believe the warning applied to him. Two touches later and the Belgian was on the floor again. Herrera let down his team. He was foolish in the extreme and later on Antonio Valencia was fortunate not to go the same way after diving in, two-footed, on Kanté, the game’s outstanding performer.

By that stage Mourinho and Conte were doing their best to ignore one another in the manner of two fourth-formers who had fallen out over a game of marbles. It was gloriously childish but also great fun. For long spells both managers stubbornly went through the pretence that the other did not exist. At other times they could be seen screaming into each other’s face, separated only by the fourth official. One argument was sufficient for Oliver to hold up play again and the body language as they received their telling-off was a picture: two grown men with their backs slightly turned so they did not have to make eye contact. It was a lesson in juvenile point-scoring.

As for the actual football – oh yes, the football – the game was always likely to swing in Chelsea’s favour once they had the extra man and it was almost a surprise they restricted themselves to only one goal during a challenging second half for their opponents.

A man down, Mourinho brought on Marouane Fellaini in place of Henrikh Mkhitaryan to give his team a more robust edge. Phil Jones was operating as a deep-lying midfielder and Ashley Young was also under instructions to drop back from the left wing. United, in other words, spent parts of the night operating with a 6-2-1 system, the paradox being that Kanté’s goal came from a gaping hole 25 yards out. David de Gea had been superb in the first half but Paul Pogba, who had a poor night, was slow to close down the shot and Rojo simply watched it go by without attempting to get his body in the way. Marcus Rashford did have a chance to catch Chelsea on the break but Thibaut Courtois kept out the shot and a grumpy night had a happy ending for Conte and his players.