Ronaldo headed home his 51st international goal in extra-time in Copenhagen, leaving the Seleccao third in Group I of the Euro 2016 qualifiers, behind the Danes and surprise leaders Albania.
"Cristiano is Cristiano. He is a winner, and there are no adjectives to describe him," Santos told reporters.
"We knew that Denmark were very strong. I think they saw the match against France and changed from their normal tactics, from a 4-3-3 to 4-4-2 trying to control the match.
"Thank God, we managed to win and I hope it's the first of many victories. I believe we definitely deserved it - we were very good in the first half and hit the post.
"The team were always seeking victory, then Cristiano took a cross from [Ricardo] Quaresma. He had other chances, but the ball wouldn't go in."