Manchester United have reportedly had an £80m bid for Napoli centre-back Kalidou Koulibaly rejected.
Koulibaly only signed a new long-term contract with Napoli in September, and his current deal does not expire until the end of the 2022-23 campaign.
Last month, it was reported that Barcelona were prepared to pay £88m to sign the Senegal international, who is believed to be a transfer target for a number of Europe's biggest clubs.
According to La Repubblica, United launched an £80m bid for the defender, but were told by Napoli that it would take an offer in the region of £89m to convince the Italian club to sell.
United were linked with a number of centre-backs during the recent summer transfer window, but Mourinho was ultimately left frustrated.