Right-Back: Dani Carvajal
Real Madrid’s defence was their weakest department in the 2018-19 season but the same defence proved to be their biggest strength last season. Right-back Dani Carvajal has been a loyal servant of the capital club and will continue to be a part of Zidane's gameplan this season as well.
The Spanish defender's ability to operate at both ends of the pitch makes him a key figure on the right flank. Like Courtois, he too doesn't have a lot of competition and is likely to feature in every single game if injuries don't keep him out.
With Achraf Hakimi now at Inter Milan, it is up to Alvaro Odriozola to step up in training and challenge his compatriot for a spot in the starting XI as the season gets underway.
Centre-back: Sergio Ramos
Sergio Ramos was the pivotal figure in Real Madrid's late surge towards the title post the lockdown and led from the front, successfully fulfilling his duties as their true leader. He is one of the world's best central defenders and will be a key player for Los Merengues in the 2020-21 season.
He has established that his technique and determination are beyond doubt. This is evident from the fact that despite being 34 years old he can keep a much younger Eder Militao on the bench. He has tremendous fitness levels and can surely start in every single game of the season; that is if he can stop himself from getting booked so often.
Centre-back: Raphael Varane
Though Sergio Ramos might've taken all the limelight thanks to his incredible performances at both ends of the pitch, Raphael Varane was a great silent partner for the Spaniard who handled everything in front of him in a composed manner last season, well almost.
He had a night to forget against Manchester City in their Champions League Round-of-16 second-leg meeting, as he was responsible for both of City's goals that night.
Apart from that, the 2018 World Cup-winner had produced solid displays at the heart of the defence for Real Madrid and will be the preferred centre-back partner for Ramos next season as well. It is expected that Zidane can rest him for cup matches and bring in Militao.
Left Back: Marcelo
When he is fully fit, Real Madrid defender Marcelo ranks among the world's finest left-backs. He has a good relationship with Zidane and now that he is back to full fitness, we expect him to start ahead of the impressive Ferland Mendy.
Left-back is a position where Real Madrid have a lot of depth, though Sergio Reguilon, who was one of the most impressive left-backs of the La Liga last term and won the Europa League with Sevilla, is set to leave the club.
The combination of Carvajal and Marcelo on the flanks is a tried and tested one and it would not be surprising to see Zidane using the same combination with the centre-back duo of Ramos and Varane at the heart of the defence for Real Madrid.