Shaun Murphy suffered a surprise early exit at the German Masters, losing 5-4 to world number 82 Jamie O'Neill after a topsy-turvy match in Milton Keynes.
O'Neill, who has reached the last-16 of a ranking event for only the third time in his career, will face either Jordan Brown or Graeme Dott in the second round, but only after completing what was a nervy decider.
Murphy, the world number seven, started well, taking the first frame with a break of 77, before O’Neill levelled the match with a knock of 75.
Why Selby’s unapologetic pursuit of greatness gives snooker headache
- German Masters 2021: Draw, schedule and latest results
- Higgins to miss German Masters after positive Covid-19 test
Both players continued to exchange frames with O’Neill in the driving seat after moving 4-3 ahead - and one from victory - with a solid 67.
But Murphy, who came into the tournament as one of the favourites, showed his class by forcing a decider, firing in a break two points short of a century to level the match at 4-4 in the best-of-nine contest.
The final frame was just as much of a see-saw as the rest of the encounter, with both players struggling for momentum, until O’Neill got himself into a 69-28 lead. Murphy fought on, requiring an improbable five snookers, but the result looked inevitable.
And despite appearing to momentarily struggle with cramp and giving Murphy a sniff to get back into the frame, O’Neill eventually closed out victory by 92 points to 41.
Ding avoids scare
Ding Junhui also needed to come through a decider to reach the last-16, coming from behind to beat Kacper Filipiak 5-4.
The 2014 winner made a shaky start, going 2-0 down before finding his feet to recover to lead 3-2.
But Filipiak, ranked 92nd in the world, was not done, breaking for 91 in the sixth frame to level the match, before moving to within a frame of victory.
Ding recovered, though, and preserved his place in the tournament by forcing a decider, which the world number nine took 55-38.
Dale stuns Maguire
Dominic Dale made a break of 70 in the decider to stun Stephen Maguire to win the thrilling contest 5-4.
Dale was trailing throughout but took the lead right at the end - when it really counted. Maguire's biggest slip-up came in the fourth frame as Dale took it despite requiring three snookers.
Dale will face Ding in the last-16.
World Seniors Championship
World Seniors Championship - White and Hendry among snooker legends eyeing glory
'Wow!' - O'Sullivan, Selby and Murphy with Shot of the Tournament contenders