Real Madrid are reportedly insisting on a buy-back clause if they allow Sergio Reguilon to sign for Manchester United.
Despite having impressed during a loan spell at Sevilla, Reguilon remains behind Marcelo and Ferland Mendy in the pecking order at the Bernabeu.
At a time when they are keen to raise funds and reduce their wage bill, Los Blancos are said to be willing to allow the left-back to link up with Man United.
However, according to COPE, the La Liga champions are insisting on being provided with the option of re-signing the Spaniard at a later date.
Although United are regarded as the frontrunners for the 23-year-old, they have little interest in agreeing to Real's most recent demand.
The Premier League giants must now decide whether they will to proceed with a £25m deal.
