Tottenham management believe Gareth Bale will be match fit within a month.
Bale underwent a medical at Madrid's training ground on Thursday, and lawyers have drawn up contracts.
Spurs hope to announce the deal on Friday, alongside the confirmation of Sergio Reguilon's permanent switch from the Bernabeu.
After a stunning spell first time around, fans will be desperate for the 31-year-old to don the Spurs shirt once again.
But they will be forced to wait with the winger still nursing a minor knee injury picked up on international duty at the start of this month.
As well as recovering from injury, Bale will also need to regain match fitness after scarcely kicking a ball in anger for the La Liga giants in recent months.
Once the formalities are completed and the deal is announced, he will be placed on an intensive training programme with Spurs medics, with the hope he could return in around four weeks.