Ukrainian Bubka Jr, a professional tennis player ranked 186th in the world and boyfriend of women's world number one Victoria Azarenka, reportedly found himself locked in a bathroom in a friend's apartment in Avenue de Camoens after a night out.
The 25-year-old apparently tried to get out of the bathroom by climbing out of the window and going back in to the next room, but fell in the attempt.
Bubka Jr suffered multiple fractures and was rushed to the Georges Pompidou hospital where his prognosis is reportedly improving.
He underwent nine hours of surgery and his condition has been described as "serious but not critical".
The 6'2" player, renowned for his powerful serve, mostly competes on the Challenger Tour but achieved his best career result last season, reaching the second round of the US Open.
His best performances this year were to reach the final at the Vancouver Challenger event and the second round of the Miami Masters.