Tottenham will name Mauricio Pochettino as the club's new manager.
Southampton was unable to convince Pochettino that they would be able to take the club to the next level.
Tottenham had also been closely linked to Ajax manager Frank de Boer, but they had long been interested in Pochettino.
Southampton finished in eighth place this past season, but they were unconvincing that he would get to keep his best players.
Tottenham had a chaotic season following their sale of Gareth Bale to Real Madrid.