He raved about the youngster, saying: "He has an idea of what he's supposed to do with the ball".
"He's a strong player and is very important for us, especially at the end of the game when we have a lot of the ball and we attack", the defender told MUTV.
"Until that, you don't know". I have worked at the top level for 35 years without any interruption, I think I'm the only one in the world who's done that.
"He wants to play all the time".
He had also enquired about the forward's availability in January in efforts to land him in exchange for Alexis Sanchez but saw his attempts rebuffed.
"I guess I delivered".
Arsene Wenger will not be taking over at Shandong Luneng when he leaves Arsenal at the end of the English Premier League season, the Chinese Super League club announced on Tuesday. [Wenger] is like a father figure. It's brilliant having a manager like that.
Mata was among many to pay tribute to the departing Gunners boss, who was at the helm of the club for an eventual 22 seasons.
But the worry remains around the cost of opting for the 47-year-old former Spain midfielder, especially as he would want to bring a big coaching staff with him.
Konstantinos Mavropanos made his debut at Old Trafford and put in a fine performance for the Gunners.
The French worldwide has been the subject of numerous reports claiming he is set to leave Old Trafford in the summer, with Jose Mourinho unable to give him assurances on more playing time.
"They're not always as you'd imagine, but it shows as well that life goes always on", Wenger said.
"And the big players do better in competition than in training, and they make a career".
And afterwards, the Belgian remarked: "I think it is good for the team. They will certainly be competing with Arsenal in the future again, and I will be following that with attention, and hopefully Arsenal come here next season and win".
I would say our central defence has done well.
Information from PA Sport was used in this report.