Chelsea have confirmed the signing of Axel Disasi from Monaco for a fee of €45 million ($49.23m).
The 25-year-old has agreed a six-year contract and becomes new head coach Mauricio Pochettino's sixth summer signing after Christopher Nkunku, Nicolas Jackson, Diego Moreira, Angelo Gabriel and Lesley Ugochukwu.
Chelsea felt compelled to strengthen their defence after Wesley Fofana had surgery on an ACL injury last month, sidelining him for several months.
Disasi, who had two years remaining on his Monaco contract, had attracted interest from a number of Premier League sides, but Chelsea moved swiftly to complete a deal.
The right-sided centre-back made three appearances for France at last year's World Cup in Qatar and will bolster Pochettino's options alongside Thiago Silva, Trevoh Chalobah and Levi Colwill with Benoit Badiashile yet to recover from a hamstring problem.
The Blues remain active in the market, with goalkeeper Robert Sanchez an imminent arrival from Brighton after the two clubs agreed a £25m deal earlier this week.
Chelsea are hopeful of signing midfielder Moises Caicedo, also from Brighton, but are yet to meet the asking price -- which is in excess of £100m -- having had two bids rejected to date, the latest of which totalled £80m.