Chelsea 'will turn their attention to Juventus central defender Matthijs De Ligt' after failing to sign Jules Kounde during the summer transfer window.
Thomas Tuchel's team have impressed during the early weeks of the season but there remains a desire to strengthen at the back.
The European champions targeted Kounde but Sevilla rejected their £43million offer and held firm to his £68m release clause.
Now, according to Italian outlet Calciomercato, Chelsea will switch their focus to Holland international De Ligt, whose release clause set at £103m becomes active at the end of this season.
Juventus would like 22-year-old De Ligt to commit to a new contract, having invested £67.8m plus add-ons when they signed him from Ajax in 2019.
However, Chelsea would reportedly be interested having concluded that a move for Paris Saint-Germain defender Marquinhos would be difficult.
Chelsea's summer move for France international Kounde, 22, was dependent on Kurt Zouma's departure from the club. Zouma joined West Ham in a £29.8m deal just before the deadline.
Sevilla's sporting director Monchi said: 'We even't satisfied with the offer, and it was linked to Chelsea selling a player. It was a decent fee but it didn't meet our criteria.'
Tuchel will be concerned that Chelsea could be left short of defensive options if contract talks with Antonio Rudiger and Andreas Christensen don't work out.
It has been reported that Danish centre back Christensen is closing in on a new £120,000 a week deal at Stamford Bridge.
Rudiger, meanwhile, is looking for closer to £200,000 a week and talks have slowed in recent weeks, with Real Madrid and PSG amongst the interested parties should the German be available on a free transfer at the end of the season.
Chelsea have still only conceded one Premier League goal this season - Mohamed Salah's penalty in the 1-1 draw with Liverpool - and top the table after five games.