Manchester United have completed the signing of defender Diogo Dalot from Porto.
The 19-year-old, who was understood to have signed for a fee of around £19m, underwent a medical with Manchester United on Tuesday.
Dalot has signed a five-year contract, with an option to extend for a further year, and becomes Jose Mourinho's second signing of the summer after Brazilian midfielder Fred joined for a fee in excess of £50m.
Mourinho said: "Diogo is an extremely talented young defender with all the qualities to quickly become a great player for this club. 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.
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"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."
Dalot said: "Joining Manchester United is an unbelievable opportunity for me. I have grown up in Porto's academy and I am so thankful for everything they have done for me. But the chance of coming to the biggest club in the world is something I just couldn't turn down.
"I'm excited about working with Jose Mourinho and learning everything I can from such a successful coach. I am looking forward to playing alongside the fantastic players in the squad."