Besides the FA Cup final against Crystal Palace at Wembley next month, United have four league games left in their campaign.
The Red Devils are currently five points behind crosstown rivals Manchester City and enemies Arsenal, and they could require winning all of their remaining games if they want to secure a top-four spot at the end of the season.
Mata writes in his weekly blog: "However, the FA Cup final is in a month's time.
"Now we know that we have five games remaining. Five finals that we want to win and I feel we are ready for, starting next Sunday against Leicester.
"They are fighting for the title and are full of confidence after the win against Swansea, showing how competitive they have been this season; having said that, we must get those three points.
"The previous game against them left us with a bitter taste and it's time to show that we can defeat them, and to make our fans happy."