Chelsea have agreed a £40m fee to sign Manchester United forward Alejandro Garnacho.
The 21-year-old Argentina international was told to find a new club by head coach Ruben Amorim at the end of last season.
Sources from United say the initial Chelsea offer was £25m, but Garnacho's transfer - which includes a 10% sell-on clause - will now be the club's fourth largest ever sale after Cristiano Ronaldo, Romelu Lukaku and Angel di Maria.
Chelsea will have spent more than £500m, including add-on clauses, on wingers in just over three years since Todd Boehly and Clearlake Capital bought the club.