Not any of Bayern Munich's high-scoring attackers, nor the powerful and potent Burak Yilmaz, and not even the magical Lionel Messi.
On Wednesday night at the Bernabeu, Real Madrid defeated Galatasaray 3-0 in the first leg of their quarterfinal tie. Almost inevitably, Ronaldo opened the scoring for Real Madrid in the ninth minute.
The goal had class written all over it. Mesut Ozil's neat through-ball found Ronaldo on the left side of the box, from where Ronaldo chipped the keeper with an exquisite finish.
Few players can finish with such skill, and even fewer defenses can hope to contain Ronaldo. Through nine matches this season in the Champions League, the Portuguese superstar has scored nine goals.
That's the most in Europe's most prestigious club competition.
So then, is it really so crazy to suggest Ronaldo might be the competition's most dangerous player this season?
Wednesday's match was another point for Ronaldo's case.