Tottenham announced on Sunday that they had agreed terms with Ajax to sign the Dutch club's captain, Jan Vertonghen.
Spurs have been tracking the Belgium defender since last season as he helped Ajax claim their second consecutive Eredivisie title.
Vertonghen is due to undergo a medical this week before completing a deal that will make him the second arrival since Andre Villas-Boas replaced Harry Redknapp as manager.
"We are delighted to announce that we have reached agreement with Ajax for the transfer of Jan Vertonghen, subject to a medical," a club statement read.
It added: "The 2011/12 campaign was the Belgium international's most successful season to date - being named Ajax captain at the start and going on to lead the Dutch side to their second straight league title.
"The centre back's impressive performances did not go unnoticed as he was named Eredivisie Player of the Year as well as Ajax's Player of the Year in a season that saw him score 10 times in 37 appearances.
"In total, Jan made 220 appearances and scored 28 goals for Ajax since making his debut for them in 2006."
Vertonghen will bolster a Spurs central defence that has been weakened over the summer following the departures of long-serving former captain Ledley King and Ryan Nelsen.
The 25-year-old is the second signing of Villas-Boas' short tenure so far after Gylfi Sigurdsson agreed a move to White Hart Lane last week.