Qualifier Mark Allen stunned former champion Ken Doherty 10-7 to reach the second round of the World Championship.
Allen was making his debut at The Crucible
The 21-year-old from Northern Ireland had led 6-3 after the first session after breaks of 92, 95 and 74.
Doherty started the second session well, levelling at 6-6 and then at 7-7 with a break of 135 - the highest of the tournament so far.
But Allen held his nerve and won the next three frames, the last after a tense safety battle, to win through.
Allen said the victory - on his Crucible debut - was the biggest of his career.
"I beat Steve Davis and John Higgins in an invitation event last year but to beat Ken Doherty in the best of 19 is definitely my best win," said Allen.
"I was really nervous early on. I can see why people come here and crumble.
"Everyone was expecting Ken to win, but being 6-3 up everyone expected me to lead from the front and win the match.
"It's a different sort of pressure and I have to admit I didn't handle it very well to start with."
I thought I did everything right with my preparations but he played superbly wel
Meanwhile Doherty, who lost any chance of securing the world number one spot for the first time, admitted he only had himself to blame.
"I'm gutted. I didn't play well - it's hard to swallow," said the 37-year-old.
"I thought I did everything right with my preparations but he played superbly well. He was very hard to contain and I did not play as well as I can.
"When you practice for six or seven hours a day it's so frustrating you start to wonder whether it's worth it."
But the Dubliner insisted he had no plans to quit the sport.
"Of course I'll carry on - it's not that desperate," he said.
Frame scores (Doherty first):
6-92 (92) 27-95 (95) 13-93 40-65 55-17 54-21 4-88 (57) 63-50 1-74 (74) 59-25 74-22 74-14 15-82 (76) 135-0 (135) 16-110 (69) 43-76 4-85 (50)