Tottenham have made a bid of about 60m euros (£53m) for Real Betis midfielder Giovani Lo Celso.
But Lo Celso has a 100m euro (£88m) release clause and it is understood Betis want to sell him for a fee closer to that amount.
Spurs will face competition for the 23-year-old Argentine with other Premier League clubs interested.
The Londoners have not signed a player since January 2018 when they paid Paris St-Germain £23m for winger Lucas Moura.
Tottenham's record signing is Davinson Sanchez - they spent £42m on Ajax's Colombia centre-back in August 2017.
Lo Celso initially joined Betis on a season-long loan in August 2018 from PSG but the La Liga club triggered their option to buy the player in April for 22m euros.
He scored 16 goals and registered six assists in 45 games for Betis last season and has been named in Argentina's squad for the Copa America, which starts on 14 June in Brazil.