Sanchez completed his move to United from Arsenal on Monday evening, with Henrikh Mkhitaryan heading the other way in one of the most high-profile swap moves of all time.
The finishing touches to the deal were made on Monday and an announcement that the two 29-year-olds had traded places was made at 6pm.
United’s new number seven Sanchez says that he has fulfilled a life-long ambition by joining United – one that he had previously revealed to legendary Old Trafford manager Sir Alex Ferguson.
“Since I was a young lad I’ve always said that my dream was to play for Manchester United, and I’m not just saying that because I’m here now and today it’s come true,” he told the club’s official website.
“I always said as a kid that I’d like to play for United and I once spoke to Sir Alex Ferguson about it.
“We chatted for around 20 minutes. And I told him that my dream was to come here to Manchester United.
“It really is a massive club, very powerful, and so now, when I got the opportunity to come here, I looked at the badge and my hairs just stood up on end because it’s a powerful club and the biggest in England.”
As for Mourinho – who is aiming to restore the glory days of Ferguson’s reign at Old Trafford – Sanchez says he is adaptable when it comes to finding a role in the team.
The Chilean will face competition from Anthony Martial and Marcus Rashford for his favoured role on the left flank, but the 29-year-old says all that matters to his is being on the pitch in the first place.
“I’m a player who likes to win everything,” he continued. “I’m very professional in everything I do. I live for football. I love football. It’s what I’m passionate about.
“I train hard every day and after a game I try to look at what went well and where I can improve.
“I really like to play down the left, through the middle… but to tell you the truth, as long as I’m playing football, I’ll fit in anywhere!
“[Mourinho] indicated it is important for the club for me to be here. I also believe that the club itself cared about me joining, and I got the impression that they were keen for me to come here and wear the number seven shirt.
“I think that also gets through to the player. Players sometimes need to feel important and loved by the club.
“That was one of the things that attracted me to come here, along with the manager, who is a person who won everything in Italy, the same as he did in Spain, and he’s a manager who likes to win.”