A Players Championship match had to be interrupted after the caller spotted an ultra-rare mistake.
William O'Connor was taking on Mario Vandenbogaerde in a last 64 match during the first Players Championship event of the season.
In the second leg, Vandenbogaerde took out a 16 checkout to level the match at 1-1.
The Belgian should have thrown first in the third leg, but O'Connor started the leg instead.
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Neither player noticed the error at first, with Vandenbogaerde completing his own throw after his opponent without any complaint.
But as he walked towards the board to collect his darts, the caller paused the match after realising what had happened.
The leg was subsequently restarted, with Vandenbogaerde correctly throwing first at the second attempt.
Commentator Abigail Davies said: "You don't see that every day, do you?
"They have just realised... Willie's just said, actually, it was my turn to throw."
Ex-PDC tour card holder Paul Nicholson, on co-commentary, added: "I can't say I've seen that before, on the stream anyway.
"I've seen it in the olden days when we had the pen, and the board on the wall. But the leg has been scrubbed."
The error has happened on several occasions previously, though it is exceptionally rare.
During the first-ever match of Premier League Darts in 2005, Wayne Mardle threw first in the opening two legs against Phil Taylor.
'Hawaii 501' lost both legs, however, and went on to lose the match to the eventual inaugural Premier League champion.
As for O'Connor, the brief pause didn't affect him as he went on to win all five legs to secure a 6-1 victory.
The Irishman currently sits in 42nd place in the PDC Order of Merit rankings, and is comfortably inside the top 32 of the two-year ProTour rankings.
Vandenbogaerde, meanwhile, is playing his first match since effectively being reinstated as a tour card holder last month.
The Belgian dropped out of the top 64 after losing his first round match at the World Darts Championship, but Dom Taylor's suspension from darts after a failed drugs test - and subsequent loss of prize money from the event - meant he dropped out of the top 64 instead.
Topics: Darts
Ryan Smart