The Spaniard was the difference in yesterday's 1-0 victory for Chelsea over the Red Devils, but the 25-year-old has claimed that United "deserve" their place at the top of the Premier League table.
"Always Man United are a team that win, win, win in the Premier League," Mata told Chelsea TV. "Maybe sometimes they don't play really well but they win, which is the important thing. They have regularity. If they win it is because they deserve it.
"If they win the Premier League almost every year, it is because they know how to play and get into the first position. Obviously for next season we need to improve in the Premier League. If we want to win we will have to win more games."
The West London outfit, who are in contention to be crowned Europa League winners, have moved back into third place in the table following Sunday's win at Old Trafford.