The Barcelona star has been criticised by some for a lack of respect in passing from the penalty spot to allow his team-mate to round off his hat-trick late in the game.
Ronaldo, though, says that he knows why the Argentine opted for such a rare tactic in their trouncing of their opponents.
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"Messi's penalty? I know why he did it but I don't have more to add," Ronaldo told reporters ahead of the first leg of his side's Champions League last-16 tie against Roma.
And while the Portuguese superstar did not go so far as to praise his Barca counterpart and perennial Ballon d'Or rival, he admits an admiration for Roma icon Francesco Totti.
"Totti is amazing, a reference for every player, and he has shown that age isn't important in football," Ronaldo enthused. "He is good for football, for kids and for everyone.
"This tie is as equal as Roma coach Luciano Spalletti says but, when the match starts, this can change. We will see at the end."