The 22-year-old Uruguayan right-back has slotted in nicely with key displays in Premier League wins over Arsenal and Watford, in the FA Cup against Shrewsbury Town and in the Europa League over FC Midtjylland, which have impressed experience teammate Mata to no end.
"I'm very pleased and I'm very happy for him because he is doing very good on the right side," Mata told MUTV.
"He's going forward, he's defending very well, he's being aggressive and he's performing like he has been playing for 10 years before.
"That is very difficult when you are young and in a stadium such as Old Trafford. He's a very competitive guy, he's very good for the team and the dressing room so we are very happy for him."