Argentina boss Gerardo Martino has praised the three first-team centre-backs at Real Madrid.
Martino coached Barcelona last season, but has revealed that he kept a close eye on their rivals from the capital.
The 52-year-old has said that he 'really likes' Sergio Ramos, Pepe and Raphael Varane, and added that he rates the latter as "the best of the lot".
"I will say three players that I like and I think they are the great secret of why the team is doing so well. I really like the central three of Real Madrid (Sergio Ramos, Pepe and Raphael Varane)," he told Un Cano.
"[Varane] is the best of the lot. Defence is essential."
Martino left Barca in the summer after failing to lead the Catalan outfit to a major trophy last season.