World Snooker Championship
18 April-4 May Venue:
Crucible Theatre, Sheffield
Live coverage each day on BBC Two, BBC Red Button and BBC Sport website (UK only), updates on BBC Radio 5 Live.
Allen is appearing in only his third World Championships
Surprise package Mark Allen booked his place in the World Championship semi-final with a 13-11 win over Ryan Day.
The Northern Irishman, who beat Ronnie O'Sullivan in the previous round, resumed with a 9-7 lead but lost the first frame to Welshman Day.
The two won alternate frames from that point on until Allen claimed the 23rd and 24th frames to secure victory.
Allen will face two-time champion John Higgins in the semi-final after he beat Mark Selby 13-12 in an epic encounter.
"I'm very glad I've won that match because I read all the newspaper articles (after beating O'Sullivan) like I always do and a lot of people were quick to shoot me down after beating Ronnie, as being a one-hit wonder," said Allen.
"So there was more pressure on me but I enjoy that, because I like to prove people wrong."
After engineering a two-frame overnight lead, Allen protected it superbly despite continual pressure from Day.
Any big occasions that have been thrown at me so far I seem to have handled pretty well
In the first frame of the session, the Welshman amassed a break of 106 after a missed red from Allen to pull himself back to within a frame.
However, in the next frame Allen restored his advantage with a 108 break - his third century of the match and one which equalled the record centuries tally for the World Championships of 68 set in 2002 and 2007.
The 19th frame could have gone either way as Allen firstly looked comfortable but gave Day a reprieve by missing a blue.
Day amassed 46 before snookering himself behind a red and subsequently taking five attempts to hit the yellow but was allowed to return to the table shortly afterwards to claim the frame.
Allen took a closely-fought frame 20 after Day had potted the final red but was unable to claim a colour and Allen cleared up to the blue for an 11-9 interval lead.
Day came out fighting again following the break and was able to once again pull himself back to within a frame of Allen, potting one of the two remaining reds from an Allen safety and clearing up.
Allen's break of 65 allowed him to claim frame 22 to edge himself closer to a semi-final place but Day once again fought back to take the following frame.
However, Allen did finally book his spot in the final four courtesy of a break of 103 and celebrated with a punch of the air.
"My dream was to one day play at the Crucible and I've done that," added Allen.
"Another dream was to play in the one-table set-up with a chance of winning the World Championship and I'm going to have that in the next match.
"Any big occasions that have been thrown at me so far I seem to have handled pretty well, so hopefully it's another one I'll be able to handle."