A women's doubles team was disqualified from the French Open after Japan's Miyu Kato hit a ball girl with a ball.
Between points, Kato sent a ball cross-court towards the ball girl, hitting her shoulder and leaving her visibly distressed.
Kato was initially given a warning by the umpire but after protests from opponents Marie Bouzkova and Sara Sorribes Tormo, they were disqualified.
She later apologised to the ball girl on Twitter.
Kato, the world number 31 in doubles, left the court in tears and was consoled by Indonesian partner Aldila Sutjiadi.
"I would like to sincerely apologize to the ball girl, my partner and my supporters because of today's unfortunate mishap," she wrote.
"It was completely unintentional. As a result, I am penalized by Roland Garros by forfeiting my prize money and points."
One official on the court compared the incident to Novak Djokovic's disqualification from the 2020 US Open, saying: "If you hit someone and they're injured, then you're responsible for that action. Even if you don't mean it, you're still responsible for that action."
Czech Bouzkova and Spain's Sorribes had taken the first set 7-6 (7-1) in the third-round encounter but were a break down at 3-1 in the second when the incident happened.
The crowd booed the decision to disqualify the 16th seeds, who were applauded off the court.
After the match, Bouzkova explained why she and Sorribes Tormo had protested to the umpire.
"It's difficult. The girl was crying for 15 minutes. I think the warning first happened because he [the umpire] didn't see she was crying and she was in that kind of pain," said the Czech.
"We told him he should look more into because the girl was crying and the ball went directly at her, it wasn't kind of a slower ball. We told them [Kato and Sutjiadi] it's very unfortunate."
According to International Tennis Federation (ITF) rules, "players shall not violently, dangerously or with anger hit, kick or throw a tennis ball within the precincts of the tournament site except in the reasonable pursuit of a point during a match (including warm-up)".
The ITF defines abuse of balls as "intentionally hitting a ball out of the enclosure of the court, hitting a ball dangerously or recklessly within the court or hitting a ball with negligent disregard of the consequences".
It is up to the discretion of the umpire and Grand Slam Supervisor if an incident warrants a single warning, which is often seen during matches, or a default from the event.
On Saturday in the women's singles, 16-year-old Mirra Andreeva received a code violation, as per Grand Slam rules, in her first-set tie-break against Coco Gauff when she thumped a ball into the crowd and it hit a spectator, although the world number 147 could have been defaulted if umpire Timo Janzen had deemed it more serious.
"Right after I thought that it was a really stupid move because it was not necessary to do that," the Russian said.
"It was really bad what I did. I had thoughts [about being defaulted], but he just gave me a warning."
In 1995, former British number one Tim Henman was disqualified for a similar incident during Wimbledon. Henman, 20 at the time, accidently struck a ball girl with a wayward ball during a men's doubles match.