Ronaldo returns to United on Tuesday for the second-leg of their Champions League tie.
"You can't change too much because we've got threats as well. But you've got to respect him, and you have to take measures to stop them. All in all, I thought we did a decent job of it over in Madrid. But then you've also got Ozil, who is a terrific player. Cristiano gets the headlines, but he's a big talent as well," Carrick told the Mail on Sunday.