The Red Devils have won their last two games in all competitions since a shock 1-0 loss to the Premier League’s basement club West Brom earlier this month.
Manchester United bounced back with a 2-0 win over Bournemouth at the Vitality Stadium last week to cement second place in the Premier League table.
The Red Devils made the trip to Wembley on Saturday for the FA Cup semi-final following a 2-0 loss to Tottenham Hotspur in the English top flight back in February.
The 20-time English champions came from 1-0 down to secure a 2-1 victory over Spurs in the semi-final clash thanks to goals from Alexis Sanchez and Ander Herrera.
Manchester United will return to Premier League action on Sunday evening with a home clash against Arsenal.
Mata, who was an unused substitute at Wembley last weekend, believes the Red Devils will need to be at the top of their game against their bitter rivals.
“This coming weekend we have a big game in the Premier League: Arsenal at Old Trafford,” Mata wrote on his personal blog One Hour Behind.
“Again, we will have to be at our best to get three important points.”
Manchester United were 2-1 winners against Crystal Palace after extra time in Louis van Gaal’s final season in charge at Old Trafford.
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