Brazilian left-back Alex Sandro has signed for Italian champions Juventus from Porto in a deal thought to be worth €26m (£18.9m).
Sandro, 24, has won six caps for his country and has been linked with Manchester United and Manchester City in the past.
He made 28 league appearances for Porto last season, scoring one goal.
Juventus begin their Serie A campaign at home against Udinese on Sunday.