The 55-year-old Cuper, whose Racing side face the champions this weekend, admits he has not seen anything that compares to the current Barca side.
"Since I've been in the world of football, I've never seen anything like it. They are excellent. The best team in the world, and a long way from the others. They have it all, they are ground-breaking," the Argentinian told Sport.
"The strikers are in midfield and vice-versa, or the defenders are the most dangerous attackers. Someone tell me if (Sergio) Busquets is a defender or midfielder, or if (Lionel) Messi is a winger, striker, playmaker or midfielder, not to mention (Javier) Mascherano.
"I've always said that perfection doesn't exist, but this Barca is as close as I've ever seen."