Napoli have been advised to knock £20million off their asking price for defender Kalidou Koulibaly by Micah Richards.
The Senegal star is considered one of the best centre-backs in Europe and is a target for Premier League trio Manchester United, Manchester City and Chelsea.
The £81million-rated man is also a target for French giants Paris Saint-Germain and recent comments by Napoli chairman Aurelio De Laurentiis hinted Koulibaly may leave this summer.
But the 29-year-old endured a torrid night against Barcelona in Saturday's Champions League last-16 tie, which the Italian club lost 3-1.
With his side already trailing 2-0, Koulibaly caught Lionel Messi while trying to clear the ball from his own area and conceded a penalty for Luis Suarez to convert.
And former England defender Richards admitted he is "not totally convinced" by Koulibaly, even going so far as to compare him to Manchester City flop Eliaquim Mangala.
“I think his [Koulibaly's] price-tag is £20milllion less,” Richards told CBS Sports .
“Everyone talks about how he is supposed to be composed on the ball, he's aggressive but I see similarities to Mangala - and he went to City and it didn't really work out for him there so I'm not totally convinced after that performance.”
Mangala moved to the Etihad in 2014 for £31.8million but struggled throughout his five years on City's books and departed for Valencia last summer.
Centre-back is an area City boss Pep Guardiola is attempting to strengthen this summer and he has already secured the services of Nathan Ake from Bournemouth for £41million.
Meanwhile, Napoli are holding out for almost double that fee for Koulibaly and Laurentiis insisted the club will not part ways with their star man for any less than the hefty valuation.
“Kalidou is a great person, I would be terribly sad to lose him. But there is a time for everything, even to move apart," Laurentiis told Sky Italia.
“But the €90million (£81million) asking price is not on the table and so it takes two to make a deal.”
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