The Manchester derby threatened to be the ultimate game of two halves.
Manchester City dominated proceedings in the first-half at Old Trafford and would have been frustrated that they were only 2-0 up heading into the break.
However, their frustration would have turned to anger after they gifted the home side a way back into the match when Claudio Bravo dropped the ball at the feet of Zlatan Ibrahimovic, who fired home.
Mourinho now had a big 15 minutes in the United dressing room.
He had just seen his side totally outplayed by Pep Guardiola’s men and needed to change something drastically. He brought off Henrikh Mkhitaryan and Jesse Lingard for Marcus Rashford and Ander Herrera.
But what did you say to his players?
Well, the Portuguese boss has revealed all.
Mourinho's team talk
"What I told them at half-time was for some of you it looks like you are trying to do what I told you not to do,” he said, per Manchester Evening News.
“And it was this: I told 20 times today never play the first station ball, never, never play because it's where they want to press. It happened 20 times during the game.
"What I said at half-time I told them in the last three days, instead of 10 minutes, much more.
"So every time we were preparing the game and every time we were analysing and trying to reduce the unpredictability of the game, we spoke about this situations.”
Mourinho's words almost worked for the Red Devils as they looked a completely different side after the interval. However, they weren’t able to turn their dominance into an equaliser as City held on to the three points.
It was the first defeat in the Mourinho era as they fell three points behind their city rivals in the Premier League table. How they react to their first setback will certainly be interesting and they've got very little time to lick their wounds.
From Thursday - where they play Feyenoord in the Europa League - they have a run of six matches in the next 18 days as the season really begins to heat up.