Serbian midfielder signs three-year contract with Old Trafford club.
Matic 'delighted' to reunite with Mourinho after completing move to Man United from Chelsea
New Manchester United midfielder Nemanja Matic intends to repay manager Jose Mourinho's faith in him as he targets Premier League and Champions League success.
The 28-year-old Serbia international has been signed by the Portuguese for a second time, having been brought back to Chelsea by him in 2014 after initially being sold by Carlo Ancelotti in 2011.
Matic leaped at the chance to be reunited with Mourinho, whom he believes will continue to improve him.
"Manchester is one of the biggest clubs in the world [but] also my wish was to train with Jose," the defensive midfielder told MUTV.
"Of course when you have a coach like him and a club like Manchester is you don't need to think a lot so my decision was very easy.
"I am very happy because we will work again together. He is a great coach and, when I worked with him before, he always took the best from me and I improve if I work with him.
"When the coach wants you to come to the club, it gives you more motivation, more possibility and I will try to...not try, I will, for sure, give my best to show that I deserve to be in this club and part of this group."
Matic has signed a three-year deal after completing a reported £40 million (Dh194.3m) move.
He has already set his sights on replicating the success he had at Stamford Bridge, where he won the league twice - once with Mourinho.
"I think that this squad is ready because it is more mature," Matic added. "They already work with Jose for one year so they know what they have to do and I am sure that this season we can do many things.
"As a member of the team, I think we can do many things. I'm sure that we will try to win the Premier League. Also, the Champions League, you never know what can happen.
"In the Champions League, everything is possible. (There are) many good teams, the best teams in Europe, so Manchester is one of the best for sure and it's very difficult to make a plan before the season starts but we will try to win every game, if it is possible."
Matic is United's third major signing of the summer after former Benfica team-mate Victor Lindelof and Romelu Lukaku.
"With Victor we have been together at Benfica. Lukaku, I didn't play with him because when I left Chelsea (first time) he just signed there and I didn't have an opportunity to train and to play with him," he said.
"But I know him because we have played many times against each other. Both of them are great players and I think they are going to help Manchester to reach the targets."
Mourinho underlined how important he believes Matic is for his vision.
"Nemanja is a Manchester United player and a Jose Mourinho player. He represents everything we want in a footballer - loyalty, consistency, ambition, team player," said the Red Devils boss.
"I would like to thank him for his desire to join us because without that, it would be impossible to have him here. I am sure our players and supporters will love him. A big welcome to our new number 31."
Matic is neither the first Serb nor the first Nemanja to play for United, following in the footsteps of former captain Nemanja Vidic.
A fearsome competitor on the pitch, Matic does not want to disappoint his compatriot when he meets him off it.
"Vidic was a great player and one of the players where I look to be similar because he had a great career," he added.
"It's great to be at the same club like him and I will try to do my best to repeat what he does because I don't want that, one day, he tells me, 'what are you doing there?'.
"So I will try to do my best for him to be happy."