Chelsea have agreed to sign Mamadou Sarr from Strasbourg but the defender will not arrived at Stamford Bridge until the summer transfer window, football.london understands.

The 19-year-old has been impressive for the French club this season and will remain there for the remainder of the campaign. Due to a limited amount of loan spots available, the Blues have chosen to strike a pre-agreement rather than bringing Sarr in this month and then sending him out elsewhere.

At the moment, Chelsea trio Andrey Santos, Caleb Wiley and Djordje Petrovic are all on loan at sister club Strasbourg and FIFA rules state that the Blues are not permitted to lend the French side any more of their players. football.london understands the fee agreed for Sarr to move to Stamford Bridge from the summer of 2025 is between £11.9million-£12.6million.

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Chelsea have a deep pool of centre-backs to choose from when everyone is fit, with the likes of Levi Colwill, Wesley Fofana, Benoit Badiashile, Axel Disasi, Josh Acheampong, plus Trevoh Chalobah and Aaron Anselmino - who were recalled from loans at Crystal Palace and Boca Juniors respectively - available to Enzo Maresca. However, at the moment, Fofana and Badiashile are ruled out with long-term hamstring injuries, hence the club's decision to bring Chalobah back this month.

Strasbourg are set to bank at least a £3.4million profit from selling Sarr, who only joined the French club last summer from Ligue 1 rivals Lyon. The move represents the first permanent piece of business between Chelsea and Strasbourg since BlueCo took over the French outfit.