Sarr, who joined the Blues in June for a reported £12 million ($24.6 million) fee, had put pen to paper on an eight-year deal with the Premier League side.

He made his debut for Chelsea in its FIFA Club World Cup group stage victory over ES Tunis, but did not feature again for the rest of the tournament.

The 19-year-old made his Ligue 1 debut for Lyon in the 2022-2023 campaign, and was a key part of Strasbourg's season last year as it qualified for the UEFA Conference League.

Sarr made 27 appearances in the French top flight, contributing to a team-high total of 10 clean sheets alongside goalkeeper Djordje Petrovic.

This is the fifth piece of business between the two clubs, which are both owned by Clearlake Capital.

Mike Penders and Kendry Paez have also joined Liam Rosenier's team on loan, while Mathis Amougou and Ishe Samuels-Smith have completed permanent transfers.

Strasbourg begins its Ligue 1 campaign on 18 August (AEST) when it faces Metz at Stade Saint Symphorien.