Chelsea have tabled a near £50 million offer for Napoli defender Kalidou Koulibaly.
Gazzetta dello Sport says the Blues have bid £47.3m up front with a further £2.7m in bonuses.
The Serie A side are thinking long and hard about the tempting offer and they have lined up Juventus defender Martin Caceres as a possible replacement for the 25-year-old.
Antonio Conte has been scouring Europe to find a frontline centre back all summer.
John Terry could have entered his final term as a Chelsea player while Branislav Ivanovic will be 33 by the time this season finishes.