The Scot watched the commanding 22-year-old in Champions League action earlier this week, and despite him being a part of his side that crashed out of the group stage of the competition, he was impressed by the centre-back.
Moyes has been tracking Mangala for some time, and has seen him emerge as one of European football’s top young players at the Estadio do Dragao.
Although Porto have publically said that he is not for sale, the Portuguese giants are known for their policy of buying players at low fees before selling them to some of Europe’s biggest clubs.
Mangala is already a member of the French national set-up, and has been lauded for his physically imposing playing style,
Moyes is thought to be concerned by the longevity of Nemanja Vidic and Rio Ferdinand’s Old Trafford careers, and is keen to land a young player to become the bedrock of his rearguard.
The United boss will have cash to spend in the New Year, with the club’s board willing to back him in a bid to avoid missing out on Champions League qualification.
A number of other clubs – including Manchester City and Chelsea – are also keen on the youngster.