"Coaches have always said to me there are times no tactics, or anything you can do, will stop quality football," Gerrard told the Daily Mail.
"That first Madrid goal, very few in the world can finish that. I applaud that goal, a magical goal by a magical player.
"The first I saw Ronaldo was in a friendly against Manchester United, for Sporting Lisbon. He tore the back out of John O'Shea. I felt sorry for him. It's been interesting to see him progress, improving year by year. I think he has changed from being an individual player out wide - a showman who sometimes did skill that didn't always hurt you - to being more direct and lethal.
"Now he does all his work around the box, between the lines where you can't pick him. I've never seen a player improve year by year so quickly."