Djokovic had just been broken at 5-5 in the first set against Pablo Carreno Busta when the world No. 1 struck a ball behind him on the court. Djokovic wouldn’t have been aiming at anyone but it hit the lineswomen — seemingly near the face — and she fell to the ground.
A discussion ensued between chair umpire Aurelie Tourte and two tournament officials.
Djokovic then had an extended conversation with the tournament referee on court before he was officially defaulted.
Moments earlier, he had smacked a ball in frustration when he was unable to convert three set points at 5-4. Then he took a tumble in the 11th game, appearing to injure his shoulder.
source: cnn.com