Tottenham have reached a £25m agreement with Fulham to sign England Under-21 left-back Ryan Sessegnon for £25m.
The deal will see Spurs midfielder Josh Onomah moving the other way.
The fee for Sessegnon, 19, who scored two goals in 35 Premier League appearances last season for relegated Fulham, could rise to £30m.
In addition, Spurs' proposed signing of Real Betis and Argentina midfielder Giovani lo Celso is likely to be on loan with an obligation to buy.
Lo Celso, who has 19 caps for Argentina, joined Betis on a permanent deal in April after spending the season on loan from Paris St-Germain. He made 45 appearances for the La Liga club in all competitions last season, scoring 16 goals.
Meanwhile, Tottenham could be set to lose midfielder Christian Eriksen as the 27-year-old Denmark international is understood to want a fresh challenge after six years at White Hart Lane.
Eriksen was linked with a move to Manchester United, but they have ended their pursuit of him.
Tottenham have ended their interest in a loan move for Barcelona midfielder Philippe Coutinho.
The 27-year-old Brazil international, who joined Barca from Liverpool in a deal worth £142m in January 2018, worked with Spurs manager Mauricio Pochettino during a loan spell with Espanyol in 2012.
He has scored 21 goals in 76 appearances for Barcelona but has been linked with moves to Arsenal, Liverpool and PSG.
The Premier League transfer window closes at 17:00 BST on Thursday.