France international defender Axel Disasi has joined Chelsea from Monaco on a six-year contract for 45m euros (£38.5m).
Disasi, 25, offers defensive cover at Stamford Bridge after Wesley Fofana sustained a serious knee injury.
He played in all 38 of Monaco’s Ligue 1 games last season.
“I am really proud to be able to be a part of this great family,” Disasi told Chelsea’s website.
“I hope to achieve very big things here. To win titles. I will do everything I can to achieve those objectives. I am very ambitious.”
The Blues, meanwhile, have agreed a fee with Brighton for goalkeeper Robert Sanchez, while several bids for the Spaniard’s team-mate Moises Caicedo have been rejected by the Seagulls.
Disasi has played four times for France, including featuring as a substitute in the 2022 World Cup final defeat against Argentina, and made 129 appearances for Monaco after joining from Stade de Reims in August 2020.