The 28-year-old has allegedly been deemed surplus to requirements at the Bernabeu ahead of the 2020-21 campaign, leading to suggestions of a summer exit.
Vazquez could, in theory, be available for a cut-price fee as his contract with Zinedine Zidane's side is due to expire in June 2021.
The attacker has contributed just three goals and two assists in 18 appearances for Los Blancos this season but has been an important squad player for the capital giants in recent years.
Here, Sports Mole looks at the shirt numbers available for Vazquez at Stamford Bridge should he arrive during this summer's transfer window.
Vazquez has worn the number 17 for Madrid in each of the last four seasons, switching from the '18' he sported during the 2015-16 campaign, having returned from a loan spell at Espanyol.
The Spaniard actually also wore '17' during the 2014-15 season at Espanyol, but he was initially handed the number 27 by Los Blancos when he first appeared for the first team.
It seems unlikely that Vazquez's usual number will be available at Chelsea next season, though, as former Madrid teammate Mateo Kovacic currently holds the 17 jersey and has been a key player this term.
The '18' could be an option with experienced striker Olivier Giroud expected to move on, while the '27' is also currently available at Stamford Bridge, having previously been worn by Andreas Christensen, who has had the number four since the start of the 2019-20 campaign.
Vazquez sported the number seven for Real Madrid Castilla but that shirt is currently held by N'Golo Kante, while the number nine, which the attacker has previously worn for Spain, is held by Tammy Abraham.
The Madrid forward has most recently worn '11' for his national side and that could be an option next season as Pedro is out of contract on June 30 and is expected to leave on a free transfer.
The '10' could also be available next season with Willian, who is also out of contract at the end of June, being tipped to depart, although it seems more likely that shirt will be reserved for a potential new striker.
The number 14, number 16 and number 21 are also vacant and could technically be filled by Vazquez, while '25', '26', '27' and '30' are also currently available ahead of the 2020-21 campaign.