Taiwo Awoniyi will spend the night in hospital where he was taken after suffering a concussion in Mainz’s home loss to Augsburg on Sunday.
The Nigeria U23 international landed awkwardly after a clash of heads with Augsburg defender Felix Uduokhai in the first half.
After a delay on the pitch where he received treatment, he was stretched off to hospital with his neck in a brace.
Mainz said Awoniyi was responsive and will spend the night in hospital.
Awoniyi, a former Golden Eaglets star, is on loan at Mainz from Liverpool who he joined in 2015.
He is yet to make an appearance for the Reds but has played 12 Bundesliga games for Mainz and has seen more game time since the restart of the league after struggling initially following his loan move last August.
There are reports that Mainz are keen on retaining the services of the 22-year-old who has also had loan spells at German side FSV Frankfurt, Dutch team NEC and Belgium sides Royal Excel Mouscron and Gent.
Florian Niederlechner scored the only goal in the first-minute to leave his old club 15th in the table, just three points above the relegation zone with three games to play.