Belgium takes on Portugal in the last 16 of Euro 2020 on Sunday, with Ronaldo having already netted five goals in three group games.
Portugal are reigning European champions, with Ronaldo their clear threat, but they also boast the likes of Diogo Jota, Andre Silva, Bernardo Silva and Bruno Fernandes.
“When you put a plan against a specific player, you can be hurt by other players,” the Belgium head coach said.
“The way that Portugal plays, they’ve got a lot of threat, they’ve got a lot of pace in behind.
“Of course Cristiano Ronaldo seems to be the player that gets the right moment, the right pass and the right chance, and you have to be always aware, but you have to defend the 10 outfield players of Portugal in the same measure.
“We need to be compact, we need to be really solid, and we need to defend as a team.
“Obviously we always think about the opposition and that’s always the case, you need to have that information, but I think we’ve got real good momentum and that’s where were concentrating.”
Portugal boss Fernando Santos was bullish about his side’s chances of progressing to the quarters, where the winner will meet Italy.
“I look at the team as whole and try to find the opposition’s flaws. Teams like Belgium and Portugal don’t have many,” Santos said.
“We know our opponent is capable and very competent but I’m firmly convinced we’re going to be better than they are.”