Summer signing Marin has failed to make an impact since his arrival from Werder Bremen in July, with injuries frustrating his start to life in West London.
The 23-year-old has made just one appearance for the Blues, appearing as a 70th-minute substitute in their 6-0 Capital One Cup thrashing of Wolves.
The attacking midfielder did not feature in former manager Roberto Di Matteo's set-up, with the likes of midfield stars Eden Hazard, Juan Mata and Oscar already at his disposal.
But Benitez has hinted he will give the German a chance to play for the European champions.
Questioned if Marin was desperate for football, Benitez told the Fulham Chronicle: "I don't believe he's desperate. He was training really well.
"He's been injured a while, but I know him. He's a good player I know from Werder Bremen.
"Hopefully we can improve fitness for many players and create competition."