Allen compiled five century breaks, but that wasn’t enough against the Crucible rookie.
Jamie Clarke has beaten fourth seed Mark Allen 10-8 in the first round of the World Snooker Championship in Sheffield.
On his debut at the Crucible Theatre, Clarke withstood a barrage of big breaks from his opponent to advance to the last 16.
The Welshman is the lowest-ranked qualifier in this year’s field, but he demonstrated a huge amount of quality to dislodge the former Masters champion.
Allen began the contest with a quick-fire brace of tons to lead 2-0, but the challenger immediately responded to remind the Antrim man that he wasn’t there to simply make up the numbers.
A terrific 136, the highest of his professional career, got Clarke on the scoreboard before a key moment occurred in the next frame which the 25 year-old stole on the black despite at one stage needing three snookers.
Allen lost the next to fall behind but fought back with another couple of century breaks to lead 5-4 at the end of the first session.
When the Tour Championship runner-up scored a 105 to open the second session – in doing so equalling the record for most hundreds in a best of 19 frames encounter at the Crucible – it looked again as if he’d pull away.
Yet, errors crept into Allen’s game, and despite getting in first in the majority of frames he couldn’t sustain his scoring prowess.
Clarke defied his inexperience and capitalised on the mounting unforced errors to claim six out of the remaining eight frames for a famous win.
For Allen, it prolongs a dismal stretch in the World Championship that has seen him reach the quarter-final stage just once from the last nine attempts.
Hyped as among one of the favourites in 2020, Allen’s quarter of the draw had opened up following the defeats to fellow seeds Jack Lisowski and David Gilbert.
Instead, it’s Jamie Clarke who will move forward to face McGill with a lucrative berth in the last eight at stake.
Clarke only turned professional in 2018 after several near misses on the international amateur scene – including runners-up finishes in the European and World Under-21 Championships.
A popular figure around the circuit, he is finally beginning to prove the level of ability that many a decade ago predicted would take him to the very top of the sport.
Elsewhere on day five, three-time champion Mark Selby made hard work of his 10-6 victory over Jordan Brown – making it a bad day all around for the Northern Irish contingent.
Selby will face Noppon Saengkham in the second round following the Thai’s superb 10-4 ousting of Shaun Murphy.
Two other ties reached their halfway points as well, with Martin Gould in outstanding form against Stephen Maguire.
The “Pinner Potter”, who was in small danger of being relegated from the Main Tour before the preliminaries last month, contributed four centuries in establishing a 7-2 overnight lead over Stephen Maguire.
Barry Hawkins enjoys a similar cushion against first-timer Alexander Ursenbacher as the last 32 nears its climax.
Those two fixtures finish on Wednesday with the second round due to begin as well.