It's official: Mamadou Sarr has signed for Real Sociedad from Chelsea. The defender's move has been confirmed by both clubs, with personal terms and registration finalised. He will now link up with his new teammates ahead of the upcoming fixtures, having completed a medical and agreed on contract terms. Mamadou Sarr had attracted interest from Chelsea, but it was Real Sociedad who secured the agreement and completed every step of the process. A deal that once seemed uncertain is now fully confirmed. This season (26/27) Real Sociedad have shipped 5 goals in 2 matches - 2.5 a game, which is well above the LaLiga average. Mamadou Sarr would be expected to come in and help tighten things up at the back. Chelsea have also been linked with Francisco Fernandes Conceicao, Lamine Camara and Iliman Ndiaye while Real Sociedad are reportedly monitoring Nayef Aguerd. Want more transfer rumours like this? Follow us on Twitter @PlayerSwitchCom for up-to-the-minute transfer news direct to your feed.