Christophe Lollichon, a former Chelsea goalkeeping coach, believes the 20-year-old Moroccan winger is already close to joining the London side.
Speaking to Ouest-France, Lollichon said: “Today, Gessime Yassine plays for Strasbourg but he is practically at Chelsea.”
Yassine moved to Strasbourg from USL Dunkerque earlier this year and has made an encouraging start to life in Ligue 1. He has scored twice in his first six league appearances this season, according to the figures reported in Sweden.
The winger's progress comes as Chelsea continue to invest in young players. The club strengthened its squad during the summer, with Morgan Rogers arriving from Aston Villa and Maxence Lacroix joining from Crystal Palace, and another addition could now be in the pipeline.
Yassine would be following a route already taken by several Strasbourg players. Chelsea and the French club are both owned by BlueCo, the consortium whose multi-club structure has facilitated movement between the two sides.
Valentín Barco, Mamadou Sarr and Emmanuel Emegha have all made the move from Strasbourg to Chelsea. Yassine could become the latest player to benefit from the relationship between the clubs if the reported transfer is completed.
Reports suggest Chelsea have made progress towards signing the winger, although the available information does not confirm that a deal has been formally agreed or provide details of a transfer fee.
For now, Yassine remains a Strasbourg player. Lollichon's comments, however, have added weight to speculation that Chelsea are working towards bringing the young winger to England.