Dalot, who only made his first-team debut in February but the 19 year-old, moved to Manchester on a five-year deal - with an option for a further year - after the Premier League runner-up  activated his release clause.

With out-of-favour Italian Matteo Darmian expected to leave Old Trafford and manager Jose Mourinho desperate to provide veteran right-back Antonio Valencia with more competition, United has turned to the Portugal Under-21 international.

Dalot made seven appearances in 2017-2018 as Porto won the Primeira Liga crown for the first time since 2012-2013 and reached the Champions League's last 16.

A Porto youth product, Dalot played in six matches of Sergio Conceicao's triumphant domestic campaign, which ended Benfica's run of four successive league crowns.

Dalot also played at left-back in Porto's goalless draw in the second leg of its UEFA Champions League tie with Liverpool.

The news comes a day after United announced it has reached an agreement to sign Brazil international Fred from Shakhtar Donetsk. 

“Joining Manchester United is an unbelievable opportunity for me," Dalot said. "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.”