Besiktas president Fikret Orman has confirmed they're "in talks" with the Germany international.
However, Hannover are also chasing Marin's signature this week, according to BILD.
The Bundesliga club are in the market for two wide midfield signings and Marin is being actively pursued.
The 25 year-old spent last season on-loan with Europa League champs Sevilla.
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