Eintracht Frankfurt are hoping to agree a new contract with Sebastian Jung after coach Armin Veh warned the club should not sell the full-back.
Jung has two years remaining on his existing deal, but has a clause in his current contract which would allow him to leave Frankfurt for a fee in the region of £2million next summer.
A proposed move to Roma reportedly fell through over the summer, while Inter Milan and Schalke have also been linked with a swoop for the 22-year-old.
However, Frankfurt are determined to ward off interest in Jung and Veh outlined the defender's importance to the top-flight new boys.
"Sebastian Jung is a valuable player for our team," Veh told Sport-BILD. "The fact he is a homegrown talent just makes him more valuable.
"You should not sell a player like that. You need to work out a new contract soon enough."
Frankfurt's general manager Bruno Hubner added: "We are out to negotiate a new contract with Sebastian Jung. We want to keep him at our club."