During the summer, the German midfielder joined Fiorentina on a season-long loan, with the option of a £4m permanent transfer but has so far failed to impress.
Marin has made just four appearances for the Italian side this season, all coming in the Europa League.
And according to reports made in Gazzetta dello Sport, he will return to Stamford Bridge in January and will try to break into Mourinho’s squad.
He failed to make a real breakthrough at the West London side following his free transfer from Werder bremen in 2012 and was loaned out to Sevilla the season after where he made just 13 starts for the Spanish side.
By Phil Wellbrook