Second-half substitute Mata dragged United back into the game in the 86th minute with a curling free-kick before an own goal from Alex Sandro secured three points for the visitors at the death.
Asked about his equaliser, Mata told MUTV: As soon as there was the free-kick in there, I had the confidence that I had to take it.
I told Ash: “Please let me take it, because I can go over the wall.”
Its very difficult for the goalkeeper because they dont see a lot [with the wall so close].
So I tried to do what I do in training a lot of times, practicing, practicing. It was important to score to make it 1-1 and, after, it led us to the 1-2.
I think because of the venue and the importance of the game, its one of the best [that Ive scored].
Jose Mourinho hailed super sub Marouane Fellaini after his impact in the second half at Juventus Stadium.
We managed to win because we played a very, very positive match and we looked for the victory to the very end. We looked for it, Mourinho said.
Fellaini changes the game, most often at home. We didnt have him in the first leg, Juventus introduced [Andrea] Barzagli to control us, but we immediately went direct and got the goals.
We introduced Juan Mata not for the free kicks, but to put the crosses in for Fellaini, who always dominates in the air.
A point or three wouldve changed little for Juventus, but three points makes a big difference to us. I suppose a draw wouldve been the right result.