Chelsea have had a bid in excess of EUR25million for defender Alessio Romagnoli rejected by AC Milan, the Italian club have confirmed.
The Blues are in the market for a new centre-half with John Terry and Gary Cahill the only fit, recognised players in that position currently on the books.
Kurt Zouma is targeting a September comeback from a serious knee injury, leaving coach Antonio Conte short of numbers in the interim.
Napoli's Kalidou Koulibaly is another reported target and Conte may opt to step up his interest in the Senegalese having been knocked back by Milan.
The Rossoneri announced via their TV channel they had rejected an offer "higher than the fee they paid Roma" for Romagnoli last year.
The 21-year-old came through the ranks at the Stadio Olimpico before an impressive loan spell at Sampdoria in the 2014-15 season led to a move to San Siro.
Conte, speaking after Saturday's 2-1 win at Watford, highlighted the need to strengthen his squad prior to the closing of the transfer window at the end of the month.
He said: "If you look now at the Chelsea squad you can see we have only four defenders, and these four defenders started today.
"[But] if [we have] one injury we are in trouble.
"The club and me we know this and we are talking every day to improve the squad but we know also that it's very difficult in this market because it's crazy.
"I don't want to buy just to buy, I want to buy the right player for Chelsea, for the present, for the future, with a good prospect. It's important we have a good investment for the future."