By Jonathan Rawcliffe
BBC Sport at The Crucible
World number 17 Ian McCulloch held off a determined comeback from last year's runner-up Graeme Dott to make the last 16 with a narrow 10-9 victory.
McCulloch performed a dance of delight when he won the last frame.
McCulloch established a 6-3 lead after Wednesday's session, and a break of 111 put him four frames ahead.
Dott fought hard to win two back, with a 120 helping his cause. At 8-5 up McCulloch remained favourite, but Dott won the next four to take the lead.
McCulloch made it 9-9, and celebrated wildly after securing the final frame.
The Preston qualifier roared with joy as the final ball went in, and jigged his way out of the Crucible arena.
McCulloch said his dramatic victory vindicated all the hours of practice put in over the season.
"You live for moments like that - they make up for a lot of things," said McCulloch.
"It shows that everything you're doing when you work hard in practice is the right thing.
"You'll always get a chance in a decider and you've just got to be man enough to take it."
G DOTT (Sco) 9-10 I McCULLOCH (Eng) 29-80 (61) 51-70 61-67 46-61 (51) 74-28 (74) 84-38 106-31 (60) 33-77 (69) 31-59 16-111 (111) 77-3 120-0 (120) 50-67 122-0 (56,55) 72-52, 85-14 (79) 80-55 (74 Dott, 55 McCulloch) 1-66 38-63 (63)