In the opening quarter-final of the day, Allen fought back to beat Mark Selby 4-3 in a classic that saw the match go down to the final black.
After Allen had gone 3-1 down through Selby’s pragmatic and often suffocating brand of snooker, the Northern Irishman battled back to send it to a last-frame decider.
Both players fended off the other’s tactical play culminating in a shootout with the final pink and black. With the black over the corner pocket, and with the pink close by, Selby missed a cannon pot but was able to get the snooker on Allen as a consolation prize.
Allen then produced an up-and-down table double to pot the pink before doubling the black into the middle pocket with aplomb to win the seven-frame, three-hour epic.
Brecel, the reigning world champion, will face Allen in Wednesday’s semi-final after the Belgian dispatched Masters finalist Ali Carter 4-1 to progress.
An early break of 73 to win the first frame set the tone and even though Carter hit back straight away, Brecel racked up three straight frames to see him into the final four.
With all four quarter-finals being played in a stacked evening of snooker, it wasn’t until nearly 23:30 local time that Shaun Murphy and Trump got their match underway.
However, this didn’t stop Murphy from taking the opening frame with a 126 break, the highest of the tournament so far, still 41 short of the ‘golden break’.
The 2005 world champion again put together a frame-defining break to go 2-0 up over Trump, before the Bristol native pulled two back in quick succession.
Murphy went back ahead with another good break but Trump was not done, sending the game to a decider with a pressurised clearance before wrapping up the win in the decider.
On last and into the early hours of the morning was Ronnie O'Sullivan and John Higgins. The old rivals have had plenty of battles over the years, but this was anything but.
O'Sullivan racked up breaks of 125, 129 and 102 to take a crushing 3-0 lead before Higgins had even potted a ball and that continued in the final frame with the seven-time world champion making 82 to wrap up the game and face Trump in the second semi-final clash.
