Ronaldo scored a brace in Los Blancos’ quarterfinal first-leg win over the defending Serie A champions.
The second was a brilliant overhead kick, that left Buffon stranded.
He said; “He’s one of those players who can have such a huge influence over the number of games and titles their sides win.
“Ronaldo is a player who is at an incredible level. Ronaldo’s worth is comparable to [Diego] Maradona, [Lionel] Messi or Pele.
“My Champions League dream isn’t possible because the best has stopped it.
He also had kind words to the Real Madrid team as a whole. “We played against champions of an incredible level,” he added.
“Their ability makes everything much more difficult and it forced us to become less precise than usual.
“It is hugely disappointing and in the end we probably won’t progress.But it is also true that in certain situations you must take stock and compliment an opponent that was stronger.”
The return leg takes place in Madrid next Wednesday.