Real Madrid left-back Sergio Reguilon is currently undergoing medical at Tottenham Hotspur ahead of a possible switch.
The 23-year-old is one of the most-sought after left-backs in Europe and was arguably Sevilla's best player as they marched to Europa League victory last season.
Despite being one of the best, he could not find a place in Zinedine Zidane's current Real Madrid side, with the likes of Marcelo and Benjamin Mendy all ahead of him.
The Spanish side has reportedly inserted a buy-back clause, which will allow them to recall the defender in future.
I understand Spurs hope to announce deals for both Gareth Bale and Sergio Reguilon tomorrow. Both players have had their MRI checks and completed most of their medicals in Spain. On the loan deal for Bale, it's closer to a 60/40 split on his wages with Spurs picking up the 40.— Alasdair Gold (@AlasdairGold) September 17, 2020
The defender is likely to be joined by former teammate at the Madrid-based side in Gareth Bale, who is also close to completing a season-long loan.
The two players will then fly to London once their medicals are done and the transfers sealed.
Mourinho and company have been forced to strengthen following a disappointing 1-0 loss to Everton in the opening match of the 2020/21 Premier League campaign.
The London club have so far made two signings; Matt Doherty joined from Wolves, while Pierre-Emile Hojbjerg signed from Southampton.
Their next Premier League match will be away to Southampton on Sunday.