Carrick revealed the Red Devils are working on ways of taming their former player and one of the world's most complete footballers.
He told The Sun: "Everyone has fond memories of Cristiano. What he's done at Madrid is incredible and he's going to take some stopping.
"I think we will need two or maybe three to mark him to be honest, he's been that good for Madrid."
The England midfielder, 31, said: "He's been sensational, to score so many goals so quickly - it's been astonishing.
"Because of Messi, he maybe hasn't had the pats on the back or the credit he deserves because the other guy has been winning everything there is to win.
"But that shouldn't take away from what he has achieved at Madrid. He's a special player."