The superstar faced Chelsea 15 times as a United player but just scored just once, in the Champions League final in 2008.
Ronaldo told Coach magazine: “Over the years I had some great battles with Ashley Cole – he doesn’t give you a second to breathe.
“He was such a tenacious player, quick, tough in the tackle – when he was at his peak”
Cristiano Ronaldo hailed Ashley Cole
“He was such a tenacious player, quick, tough in the tackle – when he was at his peak.
“You knew it would never be an easy game.”
Ronaldo also played down his rivalry with Lionel Messi, naming him as the opposing player that he most admires.
He added: “There is a big mutual respect between myself and Lionel Messi.
“The media like to make out like we have this big rivalry, but we don’t.
“It is not like we are good friends, but there is a mutual respect on both sides.”