Tottenham Hotspur confirmed Thursday they had completed the signing of Jan Vertonghen from Dutch giants Ajax after the centre-half passed his medical. The 25-year-old, who captained the Amsterdam club, had agreed terms with the London side on Sunday. Tottenham, in a statement on their Twitter feed, said Thursday: \"We are delighted to announce that @Jan_Vertonghen has completed his transfer from Ajax after passing his medical.\" Vertonghen will bolster a Spurs central defence weakened by the departures of long-serving former captain Ledley King and Ryan Nelsen. The 25-year-old is the second signing of Andre Villas-Boas\' short tenure as Spurs boss so far after Icelander Gylfi Sigurdsson agreed a move to White Hart Lane.