Chelsea are risking losing Antonio Rudiger on a free transfer next summer as they refuse to meet his demands over a new contract, sources have told ESPN.

The 28-year-old has entered the final year of his existing deal at Stamford Bridge and there has been little progress in talks over an extension since Euro 2020 finished in July.

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Sources have told ESPN Rudiger wants to double his £100,000-a-week wage to sign what would likely be the last big deal of his career.

Chelsea have so far only indicated they are willing to offer around £150,000-a-week and the impasse has alerted the interest of several top European clubs.

The financial impact of COVID-19 has limited the transfer power of many top sides and so the prospect of a Champions League winning centre-back in the peak years of his career being available for nothing will likely attract Paris Saint-Germain, Real Madrid and Juventus -- all of whom have previously expressed an interest in Rudiger.

He will be free to talk to overseas clubs directly from Jan. 1. Rudiger also previously said he discussed a move to London rivals Tottenham Hotspur last summer when Jose Mourinho was in charge.

Sources told ESPN Rudiger's preference is to stay in west London but Chelsea have previously taken a firm stance with players in similar positions, refusing to accept Willian's request for a longer contract than the club originally offered before allowing him to join Arsenal on a free last year.

Any decision over Rudiger is likely to be influenced by the club's pursuit of Sevilla FC defender Jules Kounde.

As ESPN reported last week, Chelsea remain interested in Kounde having failed to agree a deal this summer but only if Sevilla drop their recent insistence the 22-year-old's €80 million asking price is met.

The future of Thiago Silva is also a factor given he turns 37 next week and has a contract which expires at the end of the season. Chelsea have already allowed another centre-back, Kurt Zouma, to depart in a €29.4m deal to West Ham United.