By Julian Shea
BBC Sport at the Crucible
Joe Swail's early momentum deserted him at the vital moment as Anthony Hamilton came from behind to beat him 13-11.
Hamilton kept his composure to overhaul Swail
Going into the final session, Swail had made a break of over 50 in every frame he won, but despite this Hamilton had never let him get out of his reach.
Hamilton took the lead for the first time with a 54 break in the opening frame of the evening as Swail's earlier fluency eluded him.
Hamilton's assured play meant there was no likelihood of a Swail fightback.
Afterwards, Swail was left wondering what might have been after losing despite dominating the match.
"I've never scored that heavily, it's always been lacking from my game. I genuinely believed I could go all the way this year," he said.
"I dominated the first two sessions but couldn't get away from him. I probably lost every scrappy frame.
"I played well and he struggled. Coming into the last session, he could only get better, I could only get worse."
Hamilton, meanwhile, was thrilled and was honest enough to admit it was an unlikely result.
"It could have been 7-1 in the first session and 6-2 in the second, so I couldn't believe it was 8-8," he said.
"I went through the same preparation, but I felt good in the final session for no apparent reason.
"At no stage in the match did I think I stood any chance at all until 9-8 up. It's the best result I've ever had."
Second-round result (best of 25 frames):
Anthony Hamilton (Eng) 8-8 Joe Swail (NIr)
36-83 (79), 0-127 (67), 43-78 (78), 64-1,
72-26 (54), 0-98 (98), 0-74 (73), 76-13,
15-74 (68), 59-48, 0-83 (53), 68-43,
79-0 (63), 14-65 (58), 61-53, 58-40,
85-0 (54), 34-73, 64-18, 44-66, 57-42,
0-69 (69), 86-30 (86), 86-31 (61)