The Senegal international has attracted a lengthy list of admirers thanks to his performances at Napoli.
And, at 27, he is in his prime with plenty of seasons left ahead of him.
United are well aware that Koulibaly may not be available until the end of the season.
Man Utd transfer news: Top target named - but United will wait to launch move (Image: GETTY)
Man Utd transfer news: Top target named - but United will wait to launch move (Image: GETTY)
And they will therefore wait before taking a run at striking a deal for the former Genk ace.
United are currently being lead by Ole Gunnar Solskjaer, who replaced Mourinho on an interim basis in December.
Solskjaer does not expect any major incomings at Old Trafford with just over three days to go before the window slams shut.
Matteo Darmian has been heavily tipped to leave United this month, with Inter Milan and Juventus eyeing him up.
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