His agent Fali Ramadan cannot rule out a switch to Russia before next week's transfer deadline.
He told Izvestia: "Marko has some interesting proposals for loan, both Western and Eastern European clubs. He would like to play more, but we realise that at a super club like Chelsea competition will always be serious.
"Marin feels great in London, but to be consistently in the (German) national team he should play more. Soon we will discuss this with the management."