Mbappe believes that the Portuguese forward is still one of the best in the world.
"Ronaldo is not in decline," he said. "If he is in decline, then there are many more players who are facing the same plight.
"Cristiano is a great player and hopefully he remains calm against us."
"We will prepare for the game by paying attention to their strengths," he said.
"And Cristiano is one of his strengths in the team."