The Laver Cup match between Stefanos Tsitsipas and Diego Schwartzman was interrupted by a protestor who set his arm on fire.
The incident happened during the second singles match of the 2022 competition, just hours before Roger Federer was due to play for the final time in a doubles contest alongside long-time rival Rafael Nadal at London's O2 Arena.
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Laver Cup protest: What happened?
Team Europe's Tsitsipas was leading the match after taking the first set 6-2 before play was halted at the change of ends after a man gained access to the court.
The individual lit a small fire, which set his right arm ablaze, before security staff intervened to stamp out the flames and drag the protestor from the court.
The man did not appear to be badly hurt and Laver Cup organisers said the Metropolitan Police was handling the situation.
Officials checked the playing surface for damage before play was allowed to resume. Tsitsipas marched on to win 6-2 6-1 and give Team Europe a 2-0 lead over Team World, with Casper Ruud having earlier defeated Jack Sock in a three-set thriller. Ruud's French Open semifinal against Marin Cilic this year was interrupted by an environmental protestor who fastened herself to the net.
"It came out of nowhere," Tsitsipas said after the match. "I have no idea what this is all about. I never had an incident like this happen on court. I hope he is all right.
"I wanted to proceed the match without having any minor changes to the court and to make sure it was playable, especially that area. It also got in my way of viewing experience, the way I saw the court later. There was a big mark over there and I just wanted to get it cleared up."
"Once it gets to the Laver Cup, we're a very strong union."@steftsitsipas is delighted to be a part of Team Europe in London.#LaverCup pic.twitter.com/H9WECwZpmA
— Laver Cup (@LaverCup) September 23, 2022
The protest occurred on the same day that Swiss great Federer was due to play his last professional match alongside Nadal in a doubles contest against Jack Sock and Frances Tiafoe.
Who was the Laver Cup protestor?
The protestor was wearing a t-shirt with the slogan 'End UK Private Jets Now'. A website under the same name identified the man as Kai, a 20-year-old.
A tweet from the @EndUKPrivateJet account shared a photo of the incident, stating: "The liveable climate of our planet is collapsing. No one is taking it seriously."
In a video on the website, 'Kai' forewarns viewers of his plan to set his arm on fire at the Laver Cup. It is unclear whether the video was uploaded to the website or YouTube prior to the incident.
In the video, he describes the potential sight of self-inflicted suffering as "unjust" on those who would be present in the crowd, and the relevance of that message around the climate crisis.
"No-one deserves to experience suffering, especially not young, vulnerable people," he said. "And the way that we act like that principle is valid is by stopping the climate emergency as fast as possible." The video had generated 31 views on YouTube by 18:45 local time.
