Chelsea and Southampton have agreed a deal worth £53 million plus £5 million in add-ons for midfielder Romeo Lavia.
The 19-year-old, who has one senior cap for Belgium, is yet to undergo a medical at Stamford Bridge.
Last season, Romeo made 34 appearances but could not prevent the Saints from being relegated from the Premier League.
Liverpool also made a proposal for Romeo, who is poised to be the second target they lost to Chelsea after Moises Caicedo.