Boris Vukcevic is in an induced coma in a Heidelberg clinic after a road accident left the Hoffenheim midfielder fighting for his life.
The 22-year-old's car was involved in a collision with a lorry on a main road not far from the club's training ground in Sinsheim.
He was airlifted to hospital after receiving life-threatening head injuries, according to a statement from the Bundesliga club.
Vukcevic underwent surgery immediately upon arrival at the clinic and is reported to be in a 'critical condition' with no prognosis for recovery.
Vukcevic has been a regular in the Hoffenheim side since making his debut in May 2009, playing a total of 78 times, and he has also been capped by Germany's Under 21s.
"This news has shaken us," said Hoffenheim's general manager Andreas Muller. "The team, the coach and everybody here are shocked.
"Our thoughts are with Boris and his family."
Hoffenheim are due to play Augsburg in the Bundesliga on Saturday afternoon.