The Madrid coach was particularly pleased with the performances of players who have not been regular starters, including Bernardo Silva and Eduardo Camavinga, who stepped up when given the opportunity.
"I am very happy with the team, but I always want to improve," Mourinho said. "No one is where I want them to be. Obviously, we are not where I want, but there are things we are doing better today than before."
Mourinho also defended his decision to substitute Vinicius Junior, explaining that the Brazilian had not necessarily been performing badly.
"The substitution isn't the decision of a coach who isn't happy; it's the decision of a coach who has a rich bench," he said.
Mourinho acknowledged that Vinicius faced criticism from supporters but praised his defensive contribution against Leipzig, particularly his work in containing the opposition's attacking threat down the right.
"From Vinicius, more is always expected, and that he is individually decisive, but he played a match that I liked," Mourinho added.
The coach explained that bringing on fresh attacking options, including Yan Diomande and Endrick, allowed Madrid to introduce a different pace to the game. He believes supporters will need to accept that even established players may be substituted as he makes full use of his squad.
Federico Valverde also earned praise for his performance on the right, where he combined effectively with Arda Guler and Bernardo Silva.
"Fede was solid defensively. He also advanced very well," Mourinho said. "We created a lot on that side, and Fede had a fantastic match."
Mourinho admitted that using Valverde at right-back was not his preferred solution, particularly with specialist defenders available, but stressed that the midfielder's work ethic had earned him the role.
Camavinga impressed in midfield, while Bernardo Silva delivered a strong performance despite recently spending time out of the starting line-up. Mourinho said both players demonstrated the importance of competition for places.
"We return to the story of meritocracy," he said. "I am very happy with the team."
Despite the convincing scoreline, Mourinho was unhappy with the goal Madrid conceded and credited goalkeeper Thibaut Courtois with making two outstanding saves to keep his side in control.
He warned that his players could not afford to become complacent, pointing to similar lapses in previous matches.
"The goal we conceded today and the one against Sevilla came from being overconfident and from someone thinking the game was already won. I don't like that," he said.
Mourinho also praised Courtois but refused to rank him above the other goalkeepers he has coached, citing his respect for former players such as Petr Cech and Julio Cesar.
Madrid have collected nine points in the Champions League and are well placed in the race to qualify for the next stage. Mourinho believes securing as many points as possible remains essential to finishing among the competition's top eight.
Attention now turns to Sunday's El Clasico against FC Barcelona at Spotify Camp Nou.
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