The Red Devils already led a continental clash at Old Trafford through Mason Greenwood’s opener as the clock ticked past the half-hour mark.
Ole Gunnar Solskjaer’s side were looking for another and were able to work the ball to France international forward Martial.
Mata was among those looking for a pass as United’s No.9 surged forward, but he did not get one as Martial jinked his way past a couple of challenges and poked home a fine solo effort.
“I was asking for the pass during the whole play! But obviously he made the right decision to go by himself,” Mata told MUTV afterwards.
“He’s a great player. Great goal. I enjoy playing with him a lot. He gives you the ball and goes into the space. He’s a top player. If he hits top form he is very, very important for us.
“It is very important for Marcus (Rashford) and for Anthony, Mason (Greenwood) and Daniel (James) that they score goals and for us in midfield we try to help with assist and creating chances and that is what we did.”
All three of United’s forwards were on the scoresheet against Partizan, with Rashford wrapping up a convincing win.
“It is important for them for their confidence and their numbers and important for us too,” Mata added.
“We could have scored even more. We had chances to score four or five goals but the evening was a good result. The more players who score, the better for us.”
The hope at Old Trafford is that a clinical performance in Europe will provide a domestic spark, with United looking to carry their midweek form into a Premier League clash with Brighton on Sunday that will take them into the next international break.
Mata added: “Especially in the first half we played good football. We scored three goals and could have scored even more. So it was a good night and hopefully the fans enjoyed it.
“It is easier when you score early and score two or three goals in the first half you play more confidently, you have more spaces and you don’t feel tired when you are winning and you can run and run and pass and move.
“We enjoyed the first half especially, I certainly did. It was a positive night which we will try to replicate a performance like that on Sunday against Brighton.”
United will face the Seagulls sat 10th in the English top-flight, two places and a couple of points before their weekend opponents.