Tottenham completed the signing of midfielder Mateus Fernandes from West Ham for a club record fee of £85 million.
Spurs have not confirmed the length of the contract for the 21-year-old, who has played once for Portugal but is not in their World Cup squad.
Fernandes has spent the last two seasons in the Premier League with Southampton and West Ham, although each club were relegated to the Championship.
“I have long admired Mateus because he combines quality on the ball with the intensity and intelligence that is so important to the way we want to play,” said Spurs head coach Roberto de Zerbi.
“Despite his age, he already has good experience in the Premier League and has shown quality and consistency at this level.
“Mateus is comfortable under pressure, can progress with the ball, works hard for the team and has the courage to succeed in difficult moments.”
“I believe this is the ideal environment for him to continue his development.”
Tottenham beat off competition from Manchester United, who were unwilling to pay the sum agreed with Spurs – a guaranteed £85 million without add-ons.
Fernandes was seen as the north London club’s top target after Newcastle rejected a bid for Sandro Tonali.
However, Spurs have already agreed a fee of £100 million for the Italian midfielder.
They have made a quick start to the summer transfer window, with Fernandes already their fifth signing.
His arrival follows goalkeeper Martin Dubravka, as well as defenders Marcos Senesi, Andy Robertson and Jan Paul van Hecke.
“I’m very excited about this next step,” Fernandez said. Spurs are a huge club and the head coach played a key role in why I decided to join.
“When we talked, it was something special. We look at football the same way – we go out onto the field as a strong team, with fight and energy, trying to win every game.”