Real Madrid want to add some depth to the current roster and will be looking to sign a left-back next summer, according to MARCA. Per that same report, Real Sociedad's Yuri and Espanyol's Aaron would be the main candidates as Los Blancos would be interested in a backup for Marcelo, who is the undisputed starter.
Zidane has been missing a backup left-back for quite some time given that Fabio Coentrao isn't even training with the squad this year. The Portuguese defender will almost surely leave the club at the end of the season and that means Madrid will need another left-back unless Zidane decides that Nacho is the right man for the job, something quite unlikely considering that the Spanish defender has been playing more than what was initially expected because of the injuries to Varane and Pepe.
Either way, Madrid should pay close attention to the market as it would not be wise to spend another season with Marcelo being the only option for the left side of the defensive line.