The Manchester United star had high praise for the England international - who is hotly-tipped to leave Borussia Dortmund in the summer and return to his home country - but refused to be drawn on whether he could end up playing for the Red Devils.
Asked about a potential switch during an Instagram Live Q&A, Mata replied: "What do you want me to say?
"We all know that he's a great player. He's having a fantastic season at Borussia, but you know it's not my responsibility to speak about those things.
"Of course, I like him as a player but I cannot reply to that."
Although the Spanish star wouldn't comment, his teammate Marcus Rashford made no secret of his desire to link up with his countryman.
He recently said: "Hopefully we can all play together, that would be good.
"He plays off the cuff, he's creative and imaginative, these are the things you need to be world class."