The big shock of the last eight saw Brecel of Belgium, the world number ten, who trailed 10-6 heading into the final session, overcome seven-time champion O’Sullivan with a series of blistering breaks with the highlight being 110.

In the final portion of the match, world number one O’Sullivan only potted one ball as Brecel made breaks of 61, 78 and 63 after the interval to close out a 13-10 win that he described as "like a dream."

O’Sullivan, who described Brecel as "one gifted player", faces losing his world number one spot if Northern Ireland’s Mark Allen advances to the final.

A dramatic day of action at the Crucible Theatre in Sheffield also saw China’s Si Jiahui beat Scotland’s Anthony McGill in a battle of two qualifiers that went all the way to a deciding frame.

The pair were inseparable throughout the contest, with the score at the end of the first session 4-4, before the match was again level at 8-8 at the end of the second.

The match went all the way to 12-12, with Jiahui getting over the line in a tense and edgy contest at just before midnight local time as the 20-year-old became the youngest World Championship semi-finalist for 27 years and the first debutant at the event to reach the semi-final stage for 28 years.

In a battle of two four-time world champions, England’s Mark Selby overcame John Higgins of Scotland 13-7.

Selby trailed 4-1 early in the match, but in a hard-fought affair featuring high-quality safety play and several lengthy frames, he asserted his authority on the match during session two, and sealed a semi-final place with a break of 67.

Finally, Allen reached the semi-finals for the first time in 14 years when he beat qualifier Jak Jones of Wales 13-10.

Starting their final session at 8-8, the pair went to the interval at 10-10, with Jones making a break of 124 to ensure parity going into the final portion of the contest.

Allen won the next two frames after capitalising on safety errors by Jones, before he sealed the win on the colours following a frame that lasted almost an hour.

The tournament now moves to the one-table set-up in the semi-final stage, with Brecel taking on McGill, and Allen meeting Selby, in matches played over a scheduled four sessions and the best of 33 frames between tomorrow and Saturday (April 29).