Marten de Roon put AS Roma ahead before Kylian Mbappé equalised, but Donyell Malen scored twice after the interval to leave the hosts seemingly in control. Carlos Espí, Endrick and Antonio Rüdiger then struck in a remarkable late turnaround, with all three goals coming from Arda Güler corners.
Mourinho accepted responsibility for Madrid’s poor first half but praised the courage shown by his players after the tactical adjustments took effect.
“The bad first half is my fault. The good second half belongs to the players,” he said. “We lived through two matches. In the first, Roma were superior in everything; in the final 20 minutes, it was impossible to stop Madrid.”
The coach admitted Roma’s approach had surprised him and criticised the goals his team conceded, but believed the hosts could not sustain their intensity for the full match.
“They attacked us with three players down the right, and we had to make adjustments. Then we conceded a goal we cannot concede. After that, there was a kind of organised rebellion, emotionally as well,” Mourinho said.
“I know perfectly well how Gasperini’s teams play. They surprised us, but in football there are no miracles. Playing with that intensity for 90 minutes is not possible.”
Gasperini was frustrated that Roma’s excellent performance for much of the contest had been undone in a short spell.
“Three identical goals, and we froze. What is frustrating is that they scored three goals so easily. We were like mannequins in a match that had been of a completely different quality,” he said. “There is a risk of wiping out the 80 minutes we played well, but I cannot do that. Matches have to be seen through to the end.”
The Roma coach also questioned his side’s defending against Madrid’s late physical threat.
“We are a little vulnerable in that respect. Towards the end, these teams bring on physical players and settle the game. We were passive and could have defended better. Perhaps there was not enough personality, and we did not understand that the moment was crucial.”
Mourinho’s substitutions changed the contest, with Endrick heading in the equaliser before Rüdiger completed the comeback. The coach also defended the Brazilian’s future, saying: “It is impossible that he goes out on loan. I know the quality he has.”
The victory gave Madrid six points from their opening two Champions League matches, while Roma were left to recover from a defeat that Gasperini felt failed to reflect their overall performance.