Billy Joe Castle held his nerve to beat Ronnie O'Sullivan in the Snooker Shoot Out.
The world number 104 rode his luck during the first half of the match before an excellent 43 break earned him a memorable victory in front of a raucous Watford crowd.
O'Sullivan was left to rue a string of surprising misses at the start of the frame, one he went on to lose after fouling from a difficult position after Castle had laid a snooker.
O'Sullivan missed a straightforward black after a deadly long red, missed black again on his second attempt, and then an easy red which he played left-handed.
Castle was finding things similarly difficult in the early stages and O'Sullivan was back in to run-up a 30-12 lead only to run out of position with four minutes remaining.
From there, a safety exchange handed the advantage back to Castle who, with ball in hand after an excellent snooker, did what he had to do to put the frame out of reach of an opponent ranked 99 places higher and with the full support of the audience.
Earlier, Brandon Sargeant produced the most notable performance of his burgeoning career to dump out Masters finalist Ali Carter.
Trailing 63-0, Sargeant looked to have little chance but a brilliant 61 break left him needing a thin black to pull off a remarkable comeback.
The youngster missed, but a sloppy safety from Carter left him another bite of the cherry and the 22-year-old held his nerve to advantage to Sunday.
Jack Lisowski continued to hint that he could go all the way in this suitable tournament as he beat Fraser Patrick, but defending champion Thepchaiya Un-Nooh lost to Leeds veteran Peter Lines.
Anthony McGill impressed in the way he swatted aside Dominic Dale, while Aaron Hill - considered by many to be the future of snooker in Ireland - produced an upset to equal that of Castle's as he beat Kyren Wilson.
