Neymar has steadily found his feet in Russia following a four-month layoff in the build-up to the tournament, adding another goal and assist to his tally in the 2-0 win against Mexico on Monday.
Asked how he plans on doing that, however, Meunier told Globo Esporte: "I do not know how to stop him. He is very unpredictable. Neymar is probably the best player I've ever played with or against.
"Anyway, I'll do my best. I know we have a chance, but I also know that it is very complicated to stop them, not just Neymar. [Philippe] Coutinho, [Roberto] Firmino, [Gabriel] Jesus, Marcelo, the whole team.
"They have many qualities. It's complicated. We're facing the best team in the world. We have a chance, but it will be quite complicated.
"I expect a difficult game. We are not favourites to the World Cup. To beat Brazil, you have to be 100%, 120% of your mental and physical capacity. It's already a final for us. We know we have quality and collectiveness to beat them, but we also know that it will not be easy."
Neymar has been involved in 20 goals in his past 19 games in all competitions for Brazil, scoring 11 and assisting nine.