Spain defender Sergio Reguilon said he was delighted to be joining Spurs from Real Madrid alongside his idol Gareth Bale after signing a five-year deal.
Reguilon, 23, came through the youth set-up at Real and made his first-team debut in October 2018.
He was on loan at Sevilla last season and helped them win the Europa League as well as finish fourth in La Liga.
The left-back joins for an undisclosed fee but with a reported £27.5m buy-back clause.
Manchester United also spoke to Real about Reguilon but were put off by the Spanish club's insistence on the buyback clause, which allowed Spurs to step in.
Shortly after the news of the deal, Tottenham announced Bale had completed his return to the club on a season-long loan from Real.
Reguilon will wear the number three shirt for Tottenham, who play at Southampton in the Premier League on Sunday.
He recalled watching Bale for Spurs against Inter Milan in the Champions League in 2010.
"Bale has been an idol for me since that game against Inter," he said.
"Since that game in the Champions League I started to follow him, to watch YouTube videos of him and I became a big fan. I bought his shirts, his books - everything about him.
"And now being able to be here with him, in the club that raised him… I showed him on the plane the tweets that I wrote to him, and the pictures that I have from him, and he enjoyed that."
Reguilon broke into the Real first team from the academy and usurped Marcelo with dynamic displays down the left side.
"He has so much power and when he goes forward he is unstoppable. He oozes energy and he reminds me of when Dani Carvajal was starting out," said former Spain coach Robert Moreno after calling him up to the national team last year.
On his return as Real boss, Zinedine Zidane reinstated Marcelo and signed Ferland Mendy to compete with him.
Reguilon joined Sevilla on loan, where he scored three times and contributed five assists as the side finished fourth in La Liga and won the Europa League.
"Reguilon's development has been monstrous. He is a far more complete player than when he arrived," said Sevilla boss Julen Lopetegui after the 3-2 win in the final over Inter Milan.
With the equally forward-thinking Matt Doherty on the right of Tottenham's defence, Spurs manager Jose Mourinho now has the option of being more adventurous with twin attacking full-backs.
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