, De Ligt and Kounde are being eyed as potential replacements should the pair choose not to extend their stay at Stamford Bridge.
Kounde was a key summer transfer target for the Blues, but they failed to meet his release clause set by Sevilla.
Should Chelsea lose one or two of their defenders, they could return for the Frenchman.
Juventus are said to be keen to shift De Ligt's £280,000-a-week wages off the books and would sell to Chelsea knowing they're desperate to bring in defensive reinforcements.
And the 22-year-old hasn't managed to become a nailed on starter since arriving in Turin - being picked for six of their nine Serie A matches so far this season.
Defensive duo Christensen and Rudiger can negotiate pre-contracts with clubs from abroad starting from January.
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Rudiger, in particular, is attracting interest from a host of top European clubs.
Paris Saint-Germain, Bayern Munich and Real Madrid all hold a strong interest in the defender.
But his weekly wage demands could top £300,000-a-week.
And talks over a new deal with Christensen have reportedly stalled, despite the Dane expressing his desire to stay in London.
His stunning form this season will undoubtedly draw interest.
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