Spurs were not expecting to announce the deal until the weekend, but an agreement is in place subject to the formalities of the defender obtaining a work permit and completing a medical.

Spurs will pay Ajax £27m up front for the 21-year-old, with a further £14m potentially due in add-ons depending on his appearances and success at the club.

Sanchez could become the club's record signing, and their first of the summer, in what could also be a record fee for the Dutch club. Boss Mauricio Pochettino has said he wants to make four signings.

The Colombia international was named Ajax's Player of the Year last season but told the club this week that he wanted to join Spurs.

Former Tottenham and Ajax coach Martin Jol said Sanchez would need to "learn his trade" to be a success in the Premier League and could find opportunities limited at Spurs.

Jol said: "If you play for Ajax, you can play for any club in the world -- that is reality.

"He was arguably their best player. He is unbelievably quick. For a young player, he was mentally strong at Ajax.

"But to be mentally good for the Premier League, you have to learn your trade.

"Where can Sanchez play? If Pochettino plays three at the back, that's different. Then maybe [Eric] Dier or [Mousa] Dembele doesn't play. And I think Dembele is probably the best player at Spurs.

"I think the ideal situation would be to take Sanchez on loan with an option [to buy]. See if he plays. But that's impossible. Ajax gave him a contract until 2022, so they can ask whatever they want."

Davinson Sanchez in action for Ajax during the Europa League final against Manchester United. Photo by MICHAEL CAMPANELLA/Getty Images

Sanchez will be the fourth ex-Ajax player at Spurs after Jan Vertonghen, Toby Alderweireld and Christian Eriksen, who were managed by Jol in Amsterdam.

Vertonghen joined in 2012, aged 25, while Alderweireld was 24 when he moved to Atletico Madrid and made just 10 league starts before moving to Southampton on loan.

Eriksen was 21 when he joined Spurs in 2013 but he had been a regular for club and country since Jol gave him a debut aged 17.

"Toby had to learn to be tough," Jol said. "He was annoyed with me occasionally because I said: 'You're good on the ball, you're an unbelievable passer but you need to be more cynical'. As a defender, you have to be ruthless.

"He didn't play for Atletico but he knew he had to be tougher. In the Premier League or La Liga, you have to be cynical, you have to be ruthless. And he learned that. He's unbelievable now, I think he's the best centre-back in England.

"Spurs could have taken Toby from Ajax but he was probably not ready then. It is good to let them play first or buy them and let them play on loan.

"When Jan went from Ajax, he was a little bit more experienced, a little bit older and he was ready when he went to Spurs.

"And Eriksen is probably, of all these players, the biggest talent."

The arrival of Sanchez will allow Kevin Wimmer to join West Bromwich Albion in a £15m move after the Austrian defender opened talks with the Baggies this week.