His win over Day ensures him of at least £50,000 for reaching the quarter-finals enabling him to move 10,500 points above old rival Mark Selby, who lost 10-6 to Joe O’Connor in the first round at the Crucible.
A win over 2015 world champion Stuart Bingham in the last eight on Wednesday will be enough to see O’Sullivan leapfrog Luca Brecel into third spot in the rankings by securing a further £50,000.
Only an Allen run to the final would have denied O’Sullivan the chance to retain the sport’s most coveted ranking, while world No. 2 Judd Trump would have needed to claim the title for a second time if Allen reached the final, with £300,000 the difference between winning and losing the sport’s biggest match.
But Allen faces a sweat to see if he can become world No. 1 for the first time in his 19-year career after exiting the World Championship at the last-16 stage with Trump needing to reach the final to topple him from top spot.
O’Sullivan and Trump are seeded to meet in the semi-finals this year with Trump up against Welsh qualifier Jak Jones in his quarter-final on Tuesday and Wednesday.
Meanwhile, Higgins has extended his remarkable stay inside the top 16 following his brilliant 71 final-frame clearance against Allen denying the Northern Irishman on the final black after he missed a red with the rest on 62.
“It’s the best. It will live with me forever,” he told reporters. “After everything that has gone before over the last two years, to stand up under the most intense pressure is a very proud moment for me. When I came to the table, I knew that the double was my only chance, and when that went in, I knew it was on.
“I felt calm and I just tried to stay positive, and keep pushing the cue through straight. This should do wonders for me because I know I can do it, and this is the hardest place to play.”
The Scotsman – world champion in 1998, 2007, 2009 and 2011 – has been an ever-present among the game’s elite since 1995, but the former world No. 1’s remarkable 29-year run was under threat this season.
He began the tournament in 17th place (£253,500) on the provisional ranking list, but has moved up to 15th spot ahead of his meeting with 2020 finalist Kyren Wilson in the last eight.
2024 World Snooker Championship
- David Gilbert v Stephen Maguire
- Kyren Wilson v John Higgins
- Judd Trump v Jak Jones
- Stuart Bingham v Ronnie O’Sullivan
Latest provisional world rankings
(players in bold still in tournament)
- 1. Mark Allen (NI) £965,000
- 2. Judd Trump (Eng) £911,000
- 3. Luca Brecel (Bel) £690,500
- 4. Ronnie O’Sullivan (Eng) £659,000
- 5. Mark Selby (Eng) £648,500
- 6. Shaun Murphy (Eng) £498,000
- 7. Ding Junhui (Chn) £466,500
- 8. Mark Williams (Wal) £457,500
- 9. Ali Carter (Eng) £428,000
- 10. Gary Wilson (Eng) £421,500
- 11. Zhang Anda (Chn) £406,000
- 12. Kyren Wilson (Eng) £401,500
- 13. Tom Ford (Eng) £340,500
- 14. Barry Hawkins (Eng) £321,500
- 15. John Higgins (Sco) £303,500
- 16. Robert Milkins (Eng) £268,500
- – – – – – – – – – – – – – – – – – – – – – – – – – – – –
- 24. David Gilbert (Eng) £185,500
- 29. Stephen Maguire (Sco) £171,000
- 30. Stuart Bingham (Eng) £170,000
- 31. Jak Jones (Wal) £167,500