Ole Gunnar Solskjaer has made bolstering his defence a priority this summer, with the Norwegian keen on landing a dominant partner for Victor Lindelof.
Solskjaer has seen the transformative effect Virgil van Dijk has had on Liverpool and believes that Napoli star Koulibaly could have a similar influence.
And despite a lack of Champions League football being on offer at United next term, he had been hoping to persuade the man-mountain dubbed ‘K2’ to join.
Reports in Italy on Monday declared that United have had a £95million offer for the 27-year-old rebuffed by the Serie A runners-up.
But that figure comes nowhere near the £130million release clause contained within Koulibaly’s contract – which only comes into play next summer.
Napoli’s outspoken owner Aurelio de Laurentiis has no intention of parting with the former Metz and Genk star before then.
Koulibaly is widely considered to be one of the best centre-backs in the world.
And with boss Carlo Ancelotti desperate to challenge Juventus for the Scudetto next season, De Laurentiis is insisting that he won’t be sold.
The decision of Max Allegri to leave Turin this summer has given renewed hope in Naples that next season the Partenopei can finally end the Juve’s stranglehold on Serie A, 30 years after their last triumph.
Earlier this month, Ancelotti said of the Senegal stopper: “The best centre back in the world? I would say so.
“And he can still improve. He is worth €150m and he is not available for transfer.
“Koulibaly’s contract expires in 2023, in 2021 there’s a €150m clause but Napoli do not need to sell, the president [Aurelio De Laurentiis] does not want to sell and the question doesn’t come up.”
Now that the question has arisen, the response has been, and seemingly will continue to be, a resounding no.