Real Madrid defender Marcelo has asked for time to consider his future at the Santiago Bernabéu before the end of the season, having made the request during an hour-long meeting with managing director José Ángel Sánchez.
The Brazil international has made just six La Liga appearances under new manager Santiago Solari since he permanently took over from Julen Lopetegui at the end of November, with the Argentine head coach recently opting to use Sergio Reguilón as his go-to left back.
Should Marcelo decide that his 12-year spell in the Spanish capital needs to come to an end at the end of the season then Real Madrid will be on the hunt for a new defender once the transfer window reopens this summer.
Although Reguilón will keep his place in Los Blancos' first team and Theo Hernández will return from his loan in San Sebastián, here are seven full-backs across Europe who could walk straight into Marcelo's place at the Santiago Bernabéu.
1. Álex Grimaldo - S.L. Benfica
Things could have turned out very differently for Alejandro 'Álex' Grimaldo if he turned his nose up at Benfica in 2016 and opted to stay on the books at Barcelona.
While La Masia stars like Sergi Samper and Carles Aleñà are currently struggling for game time at the Camp Nou, Grimaldo has already registered 99 appearances with one of Europe's biggest clubs by the age of 22, with almost a fifth of those coming in the Champions League.
Although Grimaldo is enjoying stardom in Lisbon, his contract at the Estádio da Luz is running down and Benfica could be forced into selling him this summer while his price is at its highest.
2. Alex Sandro - Juventus
Brazil international Alex Sandro has become one of the most sought after defenders in Europe following his move to Juventus in 2015, something which has also alerted clubs to the next batch of players coming through in Portugal, namely the aforementioned Grimaldo and soon to be mentioned Alex Telles.
The 28-year-old is playing the best football of his career and could still improve before hitting his peak, but much like Marcelo at Real Madrid, his position in Turin has come under threat this season and there's been talk of a possible move away this summer.
One major boost from Real Madrid will be that the Bianconeri have actually shortlisted Marcelo as a potential transfer target for the end iofthe season, opening the door to a possible player plus cash swap in the summer transfer window.
3. Alex Telles - FC Porto
Porto knew they had stumbled onto a winning formula when Alex Sandro arrived at the Estádio do Dragão in 2011 for €9.6m.
The 28-year-old made his reputation with the club and was then shipped off to Juventus for an incredible profit, so it's no surprise that the Dragões brought in Sandro's compatriot Alex Telles just 12 months after the Brazil international moved to Turin.
Telles had spells at Galatasaray and Inter with little success before eventually landing a permanent move to Porto in 2016, where he's gone on to enjoy tremendous success and make a name for himself across the continent.
Porto aren't just limiting themselves to full back either with their Brazilian transfer policy, and centre-back Éder Militão is already being lined up by Real Madrid ahead of the summer transfer window.
4. Jose Gaya - Valencia
Spain's top flight isn't teaming with world class players who Real Madrid could snap up in an instant, but Valencia's José Gayà has been on the cusp of a step up to a side of Los Blancos' calibre for a number of seasons.
Still only 23, Gayà has already made 175 appearances for Valencia since graduating from their youth system in 2012, following in the footsteps of former players like Paco Alcácer, David Silva and Raúl Albiol on a path into the first team.
5. Marcos Alonso - Chelsea
It's impossible to talk about Real Madrid's defensive transfer targets and not mention Chelsea's Marcos Alonso, especially as he was a Madridista growing up as a youth player in Spain.
When Alonso first moved to England in 2010 he struggled to adapt, but a three-year spell in Serie A - split in two due to a short-term loan with Sunderland - quickly brought him up to pace with football at the highest level.
Since swapping Fiorentina's Artemio Franchi for Stamford Bridge, Alonso has established himself as one of the best attacking full backs around. He's been directly involved in 27 goals for Chelsea in just 111 appearances.
Seldom does a transfer window come around where Real Madrid aren't linked with bringing Alonso back to the Spanish capital, but Marcelo's exit could be the push that Los Blancos need to finally make a deal happen.
6. Júnior Firpo - Real Betis
Former Sapin Under-21 international Júnior Firpo's rise from relative obscurity to one of the most in-demand defenders in La Liga has been outstanding this season.
He had made just a handful of appearances for Real Betis coming into the 2018/19 season after four years on the books at the Benito Villamarín, but he's now become an irreplaceable part of Quique Setién's first team and has only missed one game this season that wasn't because of injury or suspension.
Firpo features slightly higher up the pitch than most left backs due to manager Setién's prefered 3-4-2-1 formation, but some of the biggest clubs in Europe are confident that the 22-year-old can replicate his current form deeper on the pitch.
7. Aarón Martín - FSV Mainz 05
If Espanyol's decision to allow Aarón Martín to leave the club on a season-long loan last year wasn't ludicrous enough, the Catalan outfit also gave Mainz the chance to sign him permanently for just €6m - a decision which Die Nullfünfer have unsurprisingly already taken.
Martín has been a stand out player for Mainz this season and is quickly establishing himself as one of the best full backs in the league, alongside Real Madrid's own Achraf Hakimi who's on loan at Borussia Dortmund.
Espanyol have included a 12% sell-on clause in their deal with Mainz, so the German club will be sure to drive up Martín's asking price if they're asked for a quote by Europe's top dogs at the end of the season.