NEW YORK — Novak Djokovic was kicked out of the U.S. Open for accidentally hitting a line judge in the throat with a tennis ball after dropping a game in his fourth-round match Sunday, a stunning end to his 29-match winning streak and bid for an 18th Grand Slam title.

As he walked to the Arthur Ashe Stadium sideline for a changeover, Djokovic — angrily smacked a ball behind him. The ball flew right at the line judge, who dropped to her knees at the back of the court and reached for her neck.