Newcastle have only scored 10, however, so they're unlikely to cause Jose Mourinho's side too much trouble at Old Trafford in an attacking sense.
United, in second place, trail neighbours Manchester City by eight points after 11 games and were beaten 1-0 by champions Chelsea in their last outing before the global break.
Benitez led the Magpies back into the Premier League by winning the Championship last season, and Mata believes they should not be underestimated despite being newly-promoted.
The 29-year-old wrote on his blog: "We return to training with the mindset on the Newcastle match and the importance of the months that lie ahead".
'These are moments in which good form of the team can be decisive for the second part of the season'.
Jose Mourinho expects his squad to be strengthened following a worldwide period of time after Paul Pogba, Marcos Rojo and Michael Carrick came back to training this week.The trio took part in a time with United's U23s on Thursday and again on Thursday night as they stepped up restoration from their respected injuries.