But the United boss thought that was the impossible dream - until a surprise phonecall told him that he had finally got his man.
The Portuguese tactician guided the Red Devils to their maiden UEFA Europa League crown in his first campaign, and will get his second underway with a Premier League test against West Ham United on Sunday.
Mourinho's mission is clear - to add to his three trophies captured in an impressive debut season at Old Trafford.
"There are not many, there are just a couple".
"When this season I got a call that Matic wants to play for me, he wants to come to Manchester United and he can make it happen, I thought he was the flawless player for me". I will go with what I have to try to win everything. And I felt that there was no chance this could happen.
Manchester United have opened talks with Zlatan Ibrahimovic over a new deal, as the Swede continues his rehabilitation from a serious knee injury.
"Not just for his qualities but also for my relationship with him. If that is going to mean better results and the title, I don't know".
"I don't think I am going to win it because I always win it in the second season".
"He doesn't need time to adapt".
Paul Pogba Not Special Insists David Moyes
Although the 32-year-old was not able to feature in any of the pre-season games, he was part of the touring squad as his comeback trail continued.
"He's 29, with five years in the Premier League and lots of experience".
Stopping short of a guarantee, Mourinho believes an encouraging pre-season and success in the Europa League last season can propel his side to further success. He's a player who gives me what I like, which is consistency.
"Matic is Matic and that's something that I really like in a player".
"If we cannot strengthen the team in these areas we have players that we can trust".
Speaking at his pre-match news conference on Friday afternoon, Mourinho said: "I'm happy with the effort the club did".
But beneath the unsmiling eyes shone an optimism about the season which was hard to hide from the questioning media.
United have been outspent by neighbours Manchester City but Mourinho has warned them it takes more than cash to be a victor.
"For large spells of last season, we felt we should have been higher up in the league than we were and performances certainly warranted that for large periods as well".
"There are obviously bigger competitions than others, but we will certainly be fighting on all fronts to win as much as we can". Step by step, we're going to fight. "It's only positive things - it's an important moment for me".
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