Novak Djokovic was shown the door at the US 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, trailing Pablo Carreño Busta 6-5 in the first set, Djokovic — who was seeded and ranked No. 1 and an overwhelming favorite for the championship — angrily smacked a ball behind him. The ball flew right at the lineswoman, who dropped to her knees at the back of the court and reached for her neck.