Manchester United have made their second signing of the summer with the capture of Portugal under-21 defender Diogo Dalot, the club have confirmed.
The 19-year-old full-back has signed a five-year deal at Old Trafford after United agreed a fee with Porto that sources have told ESPN FC is worth around £19 million.
They have already agreed a £47m deal for Brazil midfielder Fred with Shakhtar Donetsk.
Dalot, who can play at right-back and left-back, arrived in England at the weekend before having a medical at Carrington on Tuesday.
"Diogo is an extremely talented young defender with all the qualities to quickly become a great player for this club," United manager Jose Mourinho said. "He has all the attributes that a full-back needs: physicality, tactical intelligence and technical quality, combined with a Porto Academy mentality which prepares players for the maturity they need at the professional level.
"In his age group, he is the best full-back in Europe and we all believe he has a bright future ahead of him at Manchester United."
Sources have told ESPN FC that Dalot is currently recovering from a knee injury but is expected to be fit in time to join the squad for their preseason tour of the United States next month.
Dalot is highly-rated in Portugal and sources have told ESPN FC United have fought off competition from Bayern Munich and Barcelona for his signature.
He only made his first-team debut in February and still has just seven senior appearances under his belt -- including in the Champions League against Liverpool at Anfield in March.