Liverpool loanee Taiwo Awoniyi spent the night in hospital.
The 22-year-old is spending the season on loan at Mainz in Germany.
Awoniyi received treatment on the pitch and eventually came off on a stretcher.
And Mainz confirmed he would be in hospital overnight as a precautionary measure.
He has sustained a concussion and will be monitored by doctors before he is released in the coming days.