Spain international Mata netted twice in an easy 4-0 win for David Moyes' men at St James' Park.
The former Chelsea man put the visitors 2-0 to the good, curling home a free-kick six minutes before the break and then slotting home from Javier Hernandez's pass in the 50th minute.
Hernandez and Adnan Januzaj netted to round off the rout as Moyes' side moved up to sixth in the Premier League
United have claimed more points away from home than any other team in the top flight this season, but their home form has been disappointing.
Indeed, the defending champions have won just seven games at Old Trafford, with Moyes suggesting that poor form at Old Trafford could be down to the weight of expectation.
"When we look at that record, we think we should have done better at home and at Old Trafford," Mata told MUTV.
"But I think it is something to be proud of, to be the best team away from home in the league.
"Let's try to win at home, win as many games as we can until the end of the season and go higher in the table."
