The Red Devils playmaker knows Messi can singlehandedly see the La Liga title holders through in their Champions League quarter-final showdown next month.
Barcelona travel to Old Trafford for their last-eight first leg on April 10 before Manchester United go to the Nou Camp on April 16.
Mata is holding out hope United can keep Messi contained, but the Argentinian superstar is in some real form right now.
Ahead of the international break, the 31-year-old netted a stunning hat-trick away to Real Betis last night.
While his eight goals and three assists in just six Champions League appearances – one being from off the bench too – cannot be ignored.
United’s sensational comeback against PSG earned them the epic quarter-final tie.
And while now injury-free Mata is relishing the challenge, he recognises United are in for an even greater test of their credentials under Ole Gunnar Solskjaer than they faced in Paris.
While United await their return to Champions League action in just over three weeks’ time, news has emerged:
“We will have to hope that he isn’t so inspired when we play ”
“On Friday the draw for the Champions League took place, where we have been matched up with Barcelona,” Mata wrote on his blog.
“In La Liga, Barça beat Real Betis, thanks to another masterclass from Lionel Messi, and we will have to hope that he isn’t so inspired when we play against them.
“This tie will ask us to put in a huge effort, but we are ready to give our best to try to go through.
“Obviously, it is a huge challenge, but this is what this club is made of, overcoming adversity, demanding a lot from yourself and wanting to win.
“As Barça are one of the toughest opponents in world football, we will have to put all of that into practice.”
On interim manager Solskjaer’s return to the scene of United’s first experience of Champions League glory, Mata added: “For the boss, returning to Camp Nou will be very special, as well as for everyone who was there on that special night in May 1999.”
Messi has nine goals and four assists in his last six games at Barcelona, which includes two total blanks in back-to-back games at the Bernabeu against arch-rivals Real Madrid.
Mata and United, meanwhile, are hoping they get as lucky when Messi heads for Manchester.