Mark Allen and Wu Yize played out the longest frame in Crucible history during the second session of their World Championship semi-final.
A farcical 14th frame, in which eight reds were left covering the black over the bottom right corner pocket, lasted 100 minutes and 21 seconds.
It contributed to a shortened session that ended 7-7, featuring only six of the eight frames scheduled, and delayed the resumption of the other last-four match between John Higgins and Shaun Murphy.
The impasse that left the match without a ball being potted for 55 minutes - and eventually prompted referee Marcel Eckardt to warn the players - was ended when Allen fouled and nudged the black in.
That allowed Wu to pick up his only frame of the afternoon, albeit only after another 30 more minutes had elapsed.
"In a nutshell that frame is an embarrassment to snooker, and the referees' and the players' association need to try to work out a way so that never happens again," said six-time world champion and BBC pundit Steve Davis.
In response World Snooker ruled out making changes around re-racks - when a frame is restarted because of a stalemate - and said it felt that "the rule was applied correctly" by the referee.
Play will resume from 10:00 BST on Saturday, with both Wu and Allen still 10 frames away from the winning line.
Up until that point it had been a complete reversal of fortunes from Thursday, when Wu held sway with a devastating display of potting that left Allen largely confined to his chair.
The shift of momentum began immediately, Allen wrapping up the opening frame of the day after Wu completely missed the final red - which he was attempting to snick into the left corner.
Allen, 40, who is bidding to reach his maiden final and become the oldest first-time Crucible winner, was a firm second favourite in the next when the 22-year-old from China knocked in a half-century.
However Allen, who needed a snooker on the colours, eventually prevailed in another marathon frame that lasted more than an hour - when Wu was unable to drop in a long blue to the bottom right corner.
To compound matters for Wu, his opponent then knocked in a sublime 145 break - the highest of the championship so far - and drew level at 6-6 after he missed a black off its spot.
The onslaught was far from over - with Northern Ireland's Allen exhibiting all the pedigree that has helped him previously become a Masters and UK champion.
A run of 121 brought up his ninth century of the tournament - the most compiled by any player at this year's championship - before the remarkable conclusion that left commentators and pundits bemused.
'The dark side of snooker?'
Speaking on BBC Two, seven-time world champion Stephen Hendry called for the German official to end the stalemate much earlier.
"The referee's got to get involved here, in my opinion. This is the dark side of snooker," he said.
"It's been a horrendous frame but it's helped Wu Yize so much. He didn't look like winning another frame, but the ludicrous nature of this has just helped to lighten the load on him and free him up, forget what was happening to him in this session."
Kyren Wilson, the 2024 champion, added: "I think Marcel Eckardt should've called that a lot earlier.
"That game was going nowhere, quite painful, but the fight and determination from Mark Allen is still incredible."
Meanwhile, John Parrott, who won the world title in 1991, said: "I've never seen a frame like it in all my years.
"I've never seen it this bad. Mark Allen says he doesn't want a re-rack, but the referee is in charge and the referee should be in charge.
"I can understand from Mark's point of view, but the referee has the authority to do something about this."
When fellow referee Rob Spencer was dispatched from the tournament office, well into the deadlock, he warned there would be no time to restart the frame if a re-rack was called as the following match was soon due to start.
Why wasn't a re-rack called earlier?
The rules state that a re-rack can be called if:
The referee thinks a position of stalemate exists, or is being approached, or is indicated by both players, the referee shall offer the players the immediate option of re-starting the frame
If any player objects, the referee shall allow play to continue with the proviso that the situation must change within a stated period, usually after three more strokes to each side but at the referee's discretion
If the situation remains basically unchanged after the stated period has expired, the referee shall nullify all scores and reset all balls as for the start of a frame
However, in these circumstances, Eckardt would likely have felt that Allen was attempting to play progressive shots.
World number 14 Allen, who was in charge of the frame at that point, was also not keen to give away his advantage and was knocking the ball towards the baulk line - trying to force a mistake from his opponent.
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