Ole Gunnar Solskjaer may have been handed an early transfer set-back after Napoli manager Carlo Ancelotti said Kalidou Koulibaly will not be leaving the Serie A club this summer.
Jose Mourinho identified Koulibaly as one of the defenders he was interested in signing before he was sacked last December, and the Senegal international is understood to remain on United's radar.
However, Ancelotti said he anticipates the 27-year-old remaining in Naples as he discussed the Partnopei's plans for next season.
“I have a team that is already well structured and with margins for growth, even if young," he said. "In pivotal roles we are in place, the backbone is robust: two valuable goalkeepers, a reliable defence with a phenomenon like Koulibaly, the well-structured midfield with Allan, Zielinski and Fabian.
“Destined to grow, with targeted investments made in harmony with the club. The big names will all remain. Napoli is not forced to sell and make capital gains. Also, Koulibaly? Absolutely, from here it does not move.”
Koulibaly's contract with Napoli expires in 2023.
Internazionale centre half Milan Skriniar and Sampdoria defender Joachim Andersen are also being monitored by United.
United accept they might have to break the £75million world record transfer fee for a defender, amid ongoing issues at centre half.
Senior United sources previously claimed the club is prepared to spend £100m on the right profile of defender, with Raphael Varane cited as an example.
Varane, 25, is contracted to Real Madrid until 2022 and almost certainly unattainable following the reappointment of Zinedine Zidane as coach.
