Chelsea have snapped up former Nice defender Malang Sarr on a five-year deal.
The 21-year-old was available on a free transfer after leaving Nice at the end of his contract this summer and had been linked with Barcelona and Arsenal.
However, the Frenchman has now put pen to paper on a five-year deal which will keep him at Stamford Bridge until 2025, with the first of those years to be spent out on loan.
"The opportunity to sign Malang was one we could not miss," director Marina Granovskaia told Chelsea'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."
The centre-back, who is also capable of playing on the left, came through the ranks at Nice and went on to play 119 times for the first team.
Sarr becomes Chelsea's second signing in as many days following Wednesday's arrival of Ben Chilwell, and their fourth of the window so far with Hakim Ziyech and Timo Werner having also joined.