Matic adds aggression and discipline to United's midfield and he will fit right into Mourinho's preferred three-man midfield and should be a regular figure in the starting XI alongside Ander Herrera and Pogba.
But the United boss thought that was the impossible dream - until a surprise phonecall told him that he had finally got his man.
"In the Premier League I'd say seven teams will fight for the title and 20 fight for the victory in every game, every match".
He said: "When I joined Man United a year ago, I thought we needed a kind of Matic". 'I was thinking I needed three transfer windows, but after two I have a good group and the club as a football club is much better equipped. And I felt that there was no chance this could happen. "I have better conditions to deliver a better season than my first one". It's not just for his qualities but my relation with him and the way I know him'. The way I know him and the way he knows me.
He may need time, but make no mistake: writing off such a special talent now would be foolish. He's not a young guy who comes from another country.
The Red Devils' start to the season is favourable, not facing a top six side from past year until the clash at Anfield against arch rivals Liverpool on October 14. 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".
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"What I had in other clubs was more players scoring goals, what we had was midfielders, wingers scoring, central defenders scoring goals at set pieces", Mourinho said.
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. In terms of the squad, this is my second transfer window.
However, the United manager is confident that his team can improve on that, having had a good pre-season and are well prepared. We are much better organised at every level. The medical department is better, the logistics, how we organise training routines, the analysis department. Over his managerial career, Mourinho has often tasted success in his second season at a club with the domestic league title.
Both Lukaku and Matic represented more than just regular signings - by hijacking Chelsea's bid for the Belgian striker and then weakening the defending champions existing squad by securing Matic, Mourinho sent out a warning sign to the rival clubs and further underlined his title-winning aspirations. Give everything. And then normally the results are a good outcome of that work.
"So I'm happy to start on Sunday, we are ready".
"So we will go for it this season".