The 29-year-old, who won the league with Chelsea last season, has been pivotal in United's current campaign as they sit second in the league and lead their Champions League group with Matic crediting Mourinho for his strong performances.
"Mourinho is a brand, and the best coach I've ever worked with," Matic told Serbian magazine Elevate. "Sometimes it isn't easy to work with him, because he always demands more.
"Even when you play the best match in your career, he considers that you can play better in the next match.
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"I co-operated excellently with him at Chelsea, and the fact that Mourinho is the coach at Manchester was the decisive factor in my choosing my new environment."
United last won the league title in 2013 but Mourinho led the team to the Europa League and League Cup trophies last season and Matic believes that the 54-year-old has built a strong team that could win competitions.
"He has created an excellent group of players with huge potential, and everything is there for us to achieve good results," the Serbian added.
"I don't want to talk about the goals of the club, but when I mention Manchester United I think the ambitions are clear to everyone.
"We will do our best to achieve the results that previous generations had."
United trail league leaders Manchester City by two points and travel to 12th-placed Huddersfield for the first meeting between the two sides since the 1971-72 season.
(Reporting by Aditi Prakash in Bengaluru; Editing by Amlan Chakraborty)
