Liverpool have joined the interest in Napoli defender Kalidou Koulibaly.
Napoli president Aurelio De Laurentiis admits he would be prepared to sell the 28 year-old defender next summer.
Manchester United and Barcelona have long been in contact for the Senegal international.
But Sky Deutschland says Real Madrid, Bayern Munich and Liverpool are also watching developments.
Koulibaly is tied to Napoli to 2023.
