Mainz chief Rouven Schröder admits they face the prospect of selling Yoshinori Muto.
The Japan international striker is inside the final year of his current deal and Schroder says it's time for him to make a decision.
Schroder said, "Yoshi and his advisor know that we need a decision.
"There are inquiries, but so far no concrete offer."
Muto struggled for Japan in the World Cup this summer and Schroder added: "Of course he would have increased his market value even more if he had played more and scored goals."