"We have a central midfielder and a striker, so obviously another player would be one coming from the sides, but we have players and if we can not strengthen then we have people we trust".
"And last season that didn't happen much - we were focused on the goals that our striker was scoring and when he was not scoring, the team was a little bit in trouble to win matches".
Having added Romelu Lukaku, Victor Lindelof and Nemanja Matic to his squad, Mourinho is hoping United make at least one more signing before the window closes, with Gareth Bale, Ivan Perisic and Danny Rose among those linked with a move.
"There's no relation between others or a guarantee. We lost 2-1 which, I think, shows the result was really short, and one of the goals was offside so with a good VAR [video assistant referee] it would be 1-1 and extra time".
The season was only considered a success because of the three secondary trophies Mourinho delivered.
"He had a good fight against two good central defender and I am happy with this period and how he fits into - I am never exhausted to repeat - an wonderful group".
While the Red Devils did win the Europa League and EFL Cup last season, they ultimately achieved a disappointing 6th place finish in Mourinho's debut season, 24 points adrift of champions Chelsea.
Mourinho has been boosted by David de Gea staying and feels United's rivals will be more tied up with European commitments this season.
"Okay, some will have the luck to play Tuesday or Wednesday, or Saturday or Sunday, but in the end, the number of matches will be the same for everybody".
"But the football club is one thing and the team's credentials going into a a competition are another thing entirely".
As far as Mourinho's team news is concerned, the likes of Rojo, Young, Shaw and Wilson are out injured (PhysioRoom).
Such absentees means the United boss does not believe they have advanced hugely compared with this time a year ago, but he retains hope of making a fourth summer signing. If the remaining 25 per cent doesn't arrive, I will not moan. We got a central defender who can play in many other positions, which is important.
"We can but we can also play with four in the back", he said.
"We got a central midfielder, we got a striker".
"I don't say I know the league better because I have been in this league for a long time".