Louis van Gaal's side sit just four points behind the Gunners.
Mata wrote in his blog: "The last week was very positive for us and it should help the team to gather momentum for the last few games.
"Our goal is to play the Champions League the next season and all we think about right now is to win every single game. We play at home and we want to have a good game in front of our fans; we know that we can count on Old Trafford to have an extra energy.
"With the crowd's support we can be closer to the victory, although Palace got a draw at the Emirates this weekend and it's not going to be an easy game for us."