Both Mark Selby and Neil Robertson were knocked out at the first-round stage of the Masters, by Stephen Maguire and Yan Bingtao respectively.
Maguire won the Tour Championship last year but has been out of form this season and is yet to advance beyond the third round of a ranking event.
He has never gone beyond the Masters semi-finals, but was a shock first-round winner last year too when fighting back from 5-1 down to beat Robertson.
Selby, a two-time ranking tournament winner this season, had been expected to advance, and he must have gone into the match in positive mood after his half of the draw was opened up by Robertson’s exit earlier in the day. However it was far from a tight contest, with Maguire progressing 6-3.
Now Shaun Murphy, Yan, Maguire and Stuart Bingham, three of the top 16 whose seasons have been the most disappointing, are the four top-half quarter-finalists.
Next up for Maguire is a meeting with Yan, who stunned Robertson with a late rally to win 6-5.
Trailing 5-3, Yan produced breaks of 65 and 51 to force a deciding frame which he dominated to cause the first major upset of the competition and inflict another painful defeat on the reigning UK champion.
Come the 2022 edition it will be a decade since his last victory in the prestigious invitational.
The in-form Aussie appeared set to fall over the line when thundering home a brilliant long red in the decider, but a relatively straightforward pink to middle hit the far jaw and it was Yan who won the ensuing safety battle, having first taking the initiative with a long pot of his own.
It was a stop-start slog to the line, as the 20-year-old picked off the odd red without being able to build a match-winning break, but his imperious safety game kept him in command and Robertson was forced into making one mistake too many.
Leading by 39 points with 43 remaining, Yan put his opponent in a difficult snooker and Robertson could only play his escape at a hopeful pace, this time leaving the simplest of openers which went in to leave the 2012 champion needing three snookers.
With the remaining colours pinned to cushions around the table, the odds were stacked against Robertson and never did he seriously threaten to salvage a match which had been under his control before Yan turned the tide.