Hong Kong's Marco Fu won the last four frames to beat Ken Doherty 13-10 and book himself a place in the last four of the World Championship.
Fu showed great resilience in the closing stages
Resuming at 8-8, Doherty won the first frame with a break of 74 before qualifier Fu hit back with 135, his third century of the match.
Dublin's Doherty, the 1997 champion, nicked the next frame only for Fu to show his spirit down the final stretch.
He edged three close frames before finishing the game off with a 75 break.
Fu, only the second Asian player to reach the semi-finals at the Crucible after Thailand's James Wattana, will play either Peter Ebdon or Shaun Murphy in the semi-finals.
After some fluent break-building on Tuesday, Wednesday's play was largely tactical and two consecutive frames, which took the score to 10-10, lasted a total of an hour and three quarters.
After the interval, however, the 28-year-old Fu took his chances when among the balls and runs of 60 twice and 75 secured his progress.
"The frame I won to make it 10-10 was massive because Ken had come from three snookers down to steal the previous one," said the world number 24.
"The interval then came at the right time for me. I went to the dressing room, composed myself and came out really strongly. I had been prepared for it to go to the wire.
"I've never thought about winning the tournament. I came here with only one goal - to enjoy myself because I haven't been doing that.
"But working with my coach Terry Griffiths has brought a lot of improvement and the hard work is really paying off."
Doherty admitted he had missed out on a golden opportunity to repeat his 1997 World Championship triumph.
"I blew it," said Doherty. "I can't grumble because I had my chances.
"I'm very disappointed to have played the way I did after my performance against Matthew Stevens.
"I lost a lot of silly frames early in the match and sometimes they come back to haunt you.
"But I have to take my hat off to Marco. He played well tactically and made some good breaks. If he keeps doing that he can beat anyone."
K Doherty (Ire) 10-13 M Fu (HK)
83-38 94-0 32-91 (68) 28-85 53-62 63-71 1-126 (121) 69-1 12-102 (53) 89-18 (76) 80-40 (60) 104 -28 (59) 68-45 61-50 14-86 (57) 0-134 (110) 79-9 (74) 0-135 (135) 79-67 (Fu 67) 57-68 40-75 30-67 (60) 4-75 (75)