Manchester United are in the market for four defenders, however, Greek Centre-back Kostas Manolas appears to be their number one target.
The Roma centre-back has a £30.5million buy-out clause in his contract - but it only becomes active in the summer.
United are also interested in versatile Porto star Eder Militao, Napoli defender Kalidou Koulibaly and Tottenham centre-back Toby Alderweireld.