US Open 2022: Norway's Casper Rudd enters final, to face Spain's Carlos Alcaraz on Sunday

As he walked to the Arthur Ashe Stadium sideline for a changeover on Sunday, 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 line judge, who dropped to her knees at the back of the court and reached for her neck.

During a discussion of about 10 minutes near the net involving tournament referee Soeren Friemel, Grand Slam supervisor Andreas Egli and chair umpire Aurelie Tourte, Djokovic pleaded his case. Friemel didn't see what happened, and said he was not allowed to check a video replay, but was given a rundown by Egli and Tourte. Friemel said that even if Djokovic didn't intend to hurt the line judge, she was hurt, and that was enough to merit the ruling.

Djokovic quickly left the tournament grounds without speaking to reporters, posting an apology on social media hours later. "This whole situation has left me really sad and empty. I checked on the line person and the tournament told me that thank God she is feeling ok. I'm extremely sorry to have caused her such stress. So unintended. So wrong," Djokovic wrote.

Indeed, the US Tennis Association issued a statement saying that Friemel defaulted Djokovic "in accordance with the Grand Slam rulebook, following his actions of intentionally hitting a ball dangerously or recklessly within the court or hitting a ball with negligent disregard of the consequences." The USTA went on to say Djokovic forfeits the ranking points and USD 250,000 in prize money he earned in the tournament — "in addition to any or all fines levied with respect to the offending incident."