Novak Djokovic has apologised for hitting a line judge with a ball at the US Open, saying he is "extremely sorry for creating her such stress".
World number one Djokovic, 33, was disqualified from his fourth-round match against Spain's Pablo Carreno Busta because of the incident.
The Serb took a ball out of his pocket and hit it behind him, striking the woman in her throat.
"This whole situation has left me really sad and empty," said Djokovic.
"I checked on the linesperson and the tournament told me that thank God she is feeling OK.