Newcastle striker Alan Smith spent Saturday night in hospital after being accidentally struck in the face by team-mate Abdoulaye Faye.
The England international needed treatment on the pitch after he was caught by Faye during the 2-1 defeat by Chelsea at Stamford Bridge and was then substituted with 20 minutes to go.
The former Leeds and Manchester United player complained of feeling unwell during the team's flight back to the North East from London and went to hospital on the advice of the club's doctor.
Smith's agent Alex Black told The Sun: "Alan couldn't remember much after getting hurt and the club felt he should have a proper examination.
"He was allowed out on Sunday morning when he was feeling a lot better."
Smith hopes to be available for the Premier League clash against Manchester City at St James' Park on Wednesday.