Mainz sports director Rouven Schröder admits they could release Taiwo Awoniyi back to parent club Liverpool.
The Nigerian striker is on a season-long loan with Mainz, but has struggled to make an impression.
Schroder told Kicker, "Unfortunately he hasn't made the most of the chances he's been given.
"But with him, Liverpool FC and his management ultimately have the final decision."
At Mainz, Awoniyi has so far managed 146 minutes of on-field action in six Bundesliga games.