West Ham have signed Portugal Under-19s defender Goncalo Cardosa from Boavista for a reported 2.7m.
The 18-year-old centre-back has agreed a five-year contract with the Hammers.
Cardosa played 15 times for Portuguese side Boavista last season and has eight caps for Portugal at Under-19s level.
He is West Ham's fifth signing of the summer following the arrivals of striker Sebastien Haller, midfielder Pablo Fornals and goalkeepers Roberto and David Martin.
