Chelsea have completed the signing of French youngster Malang Sarr on a free transfer after the defender left Ligue 1 club Nice.
Sarr, a 21-year-old capable of playing in the centre of defence or at left-back, chose to move on from Nice at the end of the 2019-20 season following the expiration of his contract.
He has now joined Frank Lampard's side on a five-year deal, though he will spend the 2020-21 season out on loan.
"The opportunity to sign Malang was one we could not miss," Chelsea director Marina Granovskaia told the club's official website.
"He is a tremendous prospect and we will be monitoring him closely during his loan period, hoping he will soon be back at Chelsea. We are very happy to welcome him to the club today."
Sarr, who has represented France at every level from under-16 through to under-21, featured 119 times for Nice across all competitions, scoring three goals.
The defender becomes Chelsea's fourth signing of the current transfer window, following on from Ben Chilwell – who arrived from Leicester City on Wednesday – Timo Werner and Hakim Ziyech.
Brazil stalwart Thiago Silva is expected to complete his move to Stamford Bridge on a free transfer from Paris Saint-Germain in the coming days, while the Blues are also reportedly close to signing Bayer Leverkusen star Kai Havertz.