Real Madrid have suffered plenty of injuries in the start to the 2017/18 season, with their defence suffering the most. Marcelo and Theo Hernandez have both suffered injuries, while Jesus Vallejo and Dani Carvajal seem to be out for an indefinite period.
Danilo's departure to Manchester City in the summer has not been addressed, with Real Madrid now obligated to dip into the transfer market in the next transfer window.
Here are the defenders Real Madrid should buy in January.
#1 Alvaro Odriozola - Real Sociedad
Real Madrid have already been linked with the Basque defender in the past - with plenty of good reason too. The 21-year-old caught the eye towards the end of last season with his consistent performances for Real Sociedad, leading to a callup for Spain's U-21 side, which reached the final of the 2017 Euros.
In 15 appearances for the Basque side in the 2016/17 season, Odriozola created 17 chances, 4 of which turned out to assists. The right-back has kept up his form this season as well, creating 9 chances in 7 appearances, with 2 assists.
Real Madrid would very well have to pay the youngster's release clause of €40 million, although given he would be a long-term successor to Dani Carvajal, in the national team line-up as well, that would be money well spent. His attacking forays down the right wing would keep up the tradition of the best Madrid right-backs.
#2 Jorge Mere - FC Koln
Real Madrid already have 4 centre-backs this season, with Nacho and Jesus Vallejo serving as back-ups. However, Nacho's versatility means that he will often end up covering the full-back positions, leaving Vallejo as the only backup option.
Jorge Mere has been an integral part of Spain's youth team setups over the last few seasons, and a mainstay of the Sporting Gijon defence in La Liga last season, where his performances resulted in a club record sale to FC Koln for €9 million. However, the promising youngster has struggled to adapt to life in Germany and may be eyeing a return.
Real Madrid could pounce with a cut-price deal for Mere, which would bring in promising backup for very little at the moment, and a prospect to challenge for a first-team place in the future. It's a strategy pursued by Florentino Perez at the moment, and Mere ought to be the next in line.
#3 Dario Srna - Shakhtar Donetsk
The Croatian legend has already rejected a La Liga giant in the not-too recent past, with Srna opting to stay at Shakhtar Donetsk as a move to Barcelona broke down after quite advanced negotiations.
Srna has the requisite quality to play for Real Madrid, with the added bonus that he can cover both full-back positions, as Marcelo and Theo Hernandez are out injured at the same time. He would bring a wealth of experience to the club, while also not standing in the way of any promising youngsters coming through.
With Mateo Kovacic and Luka Modric already at the club, Real Madrid may find it easy to persuade the Croatian to leave Shakhtar, while also not parting with too large of a fee. Srna's tactical nous and passing range would be perfect for the requirement's of Zinedine Zidane's set-up - this would be a clever buy, if a bit unusual.
#4 Cesar Azpilicueta - Chelsea
While Real Madrid have been making some clever moves in the transfer market of late, the club has shed its 'Galacticos' policy. Florentino Perez isn't a man who shies away from spending big, and this transfer would be quite the coup - a big name, for a big fee, with the added bonus of bringing a Spanish international back to La Liga.
Azpilicueta's quality is present for all to see, he barely needs a recommendation. However, the Spanish fullback has added another bow to his arsenal, playing as a centre-back in a three-man defence, a system Zidane used unsuccessfully on occasion last season. Naturally, bringing in Azpilicueta would serve to unsettle Dani Carvajal, although his mystery heart condition may require some long-term thinking on Madrid's part.
Either way, this remains quite a fanciful transfer, as Chelsea are especially unlikely to part with a crucial first-team player. Although, Nemanja Matic...
#5 Shkodran Mustafi - Arsenal
A bit of a left-field move this, but it has been made fairly public that Shkodran Mustafi was keen on leaving Arsenal on deadline day, with his family issues in mind. However, a move to Inter Milan broke down with the Gunners insistent on recouping his fee.
Real Madrid could easily pay the €40 million Mustafi cost Arsenal, and in return, would be getting a seasoned central defender who already has La Liga pedigree with Valencia. The German could provide the competition required for Raphael Varane that could ensure the Frenchman steps up a gear, without becoming too complacent.
Buying Mustafi would hinder Jesus Vallejo's development though, although that could be negated by sending him out on loan again, albeit to a La Liga club this time, to properly test him. However, a club like Real Madrid only has place for the very best, and if Vallejo is not up to the mark, Mustafi would represent the better option.