West Ham United have announced the signing of Portuguese centre-back Goncalo Cardoso.
The 18-year-old has joined from Boavista for an undisclosed fee on a five-year deal with an option for a further year.
"He is of course a player for the future, with a lot of potential in front of him, but we feel he is ready to be with the first-team squad from both a physical and technical point of view," West Ham's director of football Mario Husillos told the club's official website.
"Our scouts in Portugal have watched his development very closely for some time now and we are very happy to have secured his transfer."
Cardoso has represented Portugal Under-19s and started 15 Primeira Liga matches last season.
He is West Ham's fifth summer signing after Roberto, David Martin, Pablo Fornals and Sebastien Haller.
The Hammers open their Premier League season at home to Manchester City on Saturday.
