United were linked with a move for the 22-year-old in the summer by Metro, before he eventually joined Porto in a £5.8 million deal from Feyenoord.
The defender has played 16 times in the Liga Sagres this season, scoring two goals and becoming a key member of the side that currently sits second in the Primeira Liga.
Now, manager Louis Van Gaal, who worked with the defender during the World Cup, is reportedly ready to make a move to bring him to Old Trafford.
Those reports come from Portuguese newspaper Record, which also claims that the defender is keen to link up with his former coach again.
Van Gaal is reportedly desperate to add defensive reinforcements during the January transfer window, having spent heavily on attacking talent during the summer. He has been linked with moves for Borussia Dortmund’s Mats Hummels by the Guardian and more recently, Valencia defender Nicolas Otamendi by the Daily Mail.