The 21-year-old Colombian is now waiting for a work permit to become a Tottenham player, after his record-breaking switch from Ajax.
The fee for the transfer could reach £38 million, exceeding the previous club record of £31.5 million for Moussa Sissoko.
Last season's player of the year at Ajax joins Pochettino's side on a six-year deal and will wear the No 6.
'It's a huge step forward in my career and will allow me to continue developing and achieving big things', the centre-back said in his first interview for to Spurs TV.
Look who's arrived...#WelcomeSanchez pic.twitter.com/h2yGPSurkP
— Tottenham Hotspur (@SpursOfficial) 23 August 2017
A message from the new boy, @daosanchez26.#WelcomeSanchez pic.twitter.com/6VM5AT4OxC
— Tottenham Hotspur (@SpursOfficial) 23 August 2017