The French boss has lauded the quality of Real Madrid's backline and singled out the young defender for special praise, insisting the 19-year-old will become "world-class"
Jose Mourinho's Los Blancos are having to contend with the absence of normal centre-back pairing Sergio Ramos (suspended) and Pepe (ankle injury), but Montanier believes they can keep faith in their teenage protege to do the job.
"Against us, Madrid can field a centre-back partnership of Varane – who is going to be world-class, in my opinion – and [Ricardo] Carvalho, a hugely experienced player," commented the 48-year-old.
"Whoever plays in goal though, we'll be up against a top keeper."
The Spanish Champions head into their fixture 16 points behind front-runners Barcelona, although the French trainer is under no illusions that Mourinho's men will still take to the field as outstanding favourites.
Montanier added: "Madrid have more than enough quality players to put out a great team. It has forwards like Benzema, Higuain and Ronaldo, as well as quality midfielders such Xabi Alonso, Ozil and Modric.
"They are dangerous all over the pitch."