The South American duo have built up a successful understanding on the right side of the United team, and Rafael has claimed that he can "feel" what the Ecuadorian will do on the pitch.
"To be honest, I think it's well recognised by everybody that Antonio has been one of my best friends at the club," Rafael told The Mirror.
"That's not to disrespect anyone, but I think we've created a very good understanding on the pitch. I can feel what he wants to do and vice versa, and that's probably the reason why we have so much understanding on the pitch."
United face Everton in the Premier League on Sunday.