The Heidelberg University Hospital confirmed the 22-year-old was still in an induced coma and a prognosis was "not possible at this stage" and would "likely only be possible in the next weeks".
Vukcevic was injured in a car crash on Friday which occurred while the player was on his way to training. His Mercedes-Benz was involved in a collision with a lorry on a main road not far from the club's training ground in Sinsheim.
A statement from Heidelberg University Hospital, posted by Hoffenheim on their official website, read: "Boris Vukcevic was taken to Heidelberg University Hospital after his accident on Friday 28 September 2012 and is being treated there.
"After two operations on the head and brain, his condition is critical but stable. A prognosis is not possible at this stage and will likely only be possible in the next weeks. Vukcevic is in a coma. His doctors are doing everything to protect the brain from further damage."
Vukcevic, who was born in Croatia but has represented Germany at Under-21 level, has been a regular in the Hoffenheim side since making his debut in May 2009.
The club fulfilled their Bundesliga fixture against Augsburg on Saturday, managing a 0-0 draw, and the players have now been given two days off before returning to training on Tuesday.