By Julian Shea
BBC Sport at The Crucible
Peter Ebdon and Ian McCulloch tussled for over seven hours before McCulloch claimed a 10-8 first round victory.
Former world champion Ebdon crashed out on Monday
Honours were even at 4-4 at the end of the morning session, which included the tournament's longest frame yet at over 48 minutes.
There was never more than one frame dividing the pair, and at 8-8 McCulloch looked to have blown several chances to take the frame but ended up winning it.
Seizing his chance, he took the final frame 69-34 to seal a hard-earned win.
Ebdon, the 2002 World Champion, was typically gracious in defeat after his dramatic exit.
"He played superbly well. He was very, very gritty. If I'd won, the first thing I'd have said is 'you didn't deserve to lose'. He didn't," he said.
"He's a very tough match player and his safety was good throughout. He held himself together remarkably well towards the end.
"I came here in good form and I've worked hard but he fully deserved it."
A jubilant McCulloch added: "When the draw came out and I saw Peter win in Ireland and reach the semis in Scotland, I knew I had a really tough match on my hands.
"I've had a hard season but days like this make it all worthwhile."
He also revealed the secret behind his grimaces after missing potentially vital shots.
"I was thinking what my wife would say if I lost," he joked.
First round result (best of 19 frames):
P Ebdon (Eng) 8-10 I McCulloch (Eng)
24-91 (67), 92-9, 88-0 (88), 32-70 (61), 45-91 (69), 95-38, 61-67 (53 Ebdon), 100-19 (71), 69-1, 42-78 (71), 102-17 (62), 18-102 (72), 95-5 (62), 20-72 (65), 61-60 (57 Ebdon, 60 McCulloch), 36-70, 1-84, 34-69 (69)