Mainz manager Thomas Tuchel could end the loan stay of Celtic's Morten Rasmussen in order to reduce the size of his squad.
The Bruchwegstadion boss is considering the future of the striker during the Bundesliga's winter break.
Tuchel has surprisingly guided Mainz to second place at the midway point of the campaign, but he is aware that some members of his squad are not part of his plans.
Rasmussen is one such man after making just five appearances since his August arrival from Celtic and the Denmark international could be returning to Scotland.
Tuchel told BILD: "If your squad has a size of 28 players, you cannot satisfy every single player.
"Therefore we want to reduce the squad. One of these players might be Morten Rasmussen.
"He has not fitted into our intensive style of playing."
Mainz sporting director Christian Heidel said at the start of December that the club would not be accepting the option to buy Rasmussen after his loan.