Senegal defender Papy Djilobodji has signed a four-year deal with Chelsea, Nantes have announced.
The Premier League champions made their move for the 27-year-old after seeing their overtures for Everton's John Stones repeatedly rebuffed.
Chelsea have conceded nine goals in four games in accruing four points to sit eight adrift of leaders Manchester City.
Chelsea were still to officially confirm the deal.
Ligue 1 club Nantes said in a statement on their website: “FC Nantes, Chelsea and Papy Djilobodji have reached an agreement for the transfer of the Senegalese international. Papy Djilobodji is a player of Blues for the next four seasons.
“FC Nantes extends its congratulations and wishes him well for the rest of his career.”
Reports in the French media on Monday said a deal of around €3 million had been completed for Djilobodji. It is less than 10 per cent of the sum offered for Stones.
Djilobodji had one year remaining on his Nantes contract and his likely switch to Jose Mourinho’s Chelsea is unexpected.
It has been reported other Premier League clubs rejected the opportunity to sign him, but now he is playing for the defending champions and in the Champions League.
The Blues have signed goalkeeper Asmir Begovic, left-back Baba Rahman and striker Radamel Falcao on loan from Monaco — all like-for-like replacements for the departed Petr Cech, Filipe Luis and Didier Drogba.
Pedro was added from Barcelona and Victor Moses signed a four-year deal before joining the ranks of loan departures, making a season-long switch to West Ham.
Rumoured interest in Paul Pogba of Juventus refuses to subside, but it would take an astronomical fee to land the Frenchman, and Chelsea will require a U-turn from Everton to return for Stones.
Mourinho insisted Chelsea would not panic in the closing hours of the transfer window.
And Djilobodji may represent little more than a fall-back option as his pedigree is not quite at the standard Mourinho would wish for.
It may also indicate Chelsea are prepared to return for Stones in January or next summer.