The 21-year-old will be fighting Vertonghen and Toby Alderweireld for a place in the back line following his switch from Ajax, which reportedly cost £42m.
Vertonghen is well aware of the Colombian's strengths having spoken to his contacts at Ajax, where he played for six years before joining Tottenham in 2012.
"I know people who know him and they are all very positive, they rate him very highly," the defender told the club's official matchday programme. "It's always nice to have new players in the squad and we're looking forward to seeing him training. It will mean more competition for places but that's what football is all about.
"Obviously he's coming from Ajax so we have something in common, along with Christian [Eriksen] and Toby [Alderweireld] who also played for them in the past.
"I'd say that the Premier League is more physical than the Dutch league, but Sanchez looks like he has that physicality so I'm sure he'll do well here."
Tottenham's first game back after the international break will be a trip to Goodison Park to face Everton this Saturday.