Chelsea have completed the signing of French defender Mamadou Sarr from RC Strasbourg.
The 19-year-old, who was pursued by a number of clubs, has signed an eight-year contract at Stamford Bridge.
He made 28 appearances last season for Strasbourg and has played for France at various age levels, mostly recently Under-20.
Sarr began his career at Lyon and moved to Strasbourg last summer.
Mamadou was a regular for Strasbourg during the 2024/25 campaign and played a key role in the French team securing qualification for European football next season.
The 19-year-old made 28 appearances across all competitions and helped the club seal a place in next season’s UEFA Conference League play-off.
Mamadou first showed his high potential in the academy of RC Lens before joining Lyon. Having progressed through the club’s youth ranks, he made his senior debut during the penultimate game of the 2022/23 season.
The influential defender was handed two more senior outings during the following campaign before he embarked on a five-month loan spell at Belgian club RWD Molenbeek.
Mamadou, a France Under-20 international, joined Strasbourg last August and quickly established himself as a regular starter in defence. He made 27 starts in Ligue 1 as Strasbourg claimed a seventh-place finish.
His talent has been recognised by his country as he has been capped at various youth levels, with his latest appearances coming for France’s Under-20 side.