Mark Williams came from behind three times before rattling in a 142 break to beat Dominic Dale in the quarter-finals of the Australian Goldfields Open.
Williams was never ahead in the all-Welsh quarter-final in Bendigo until he swept to victory in the ninth frame with his fourth century of the match.
Williams now faces Ken Doherty, who saw off Mark Selby 5-3 in Friday's other quarter-final.
The Irishman had not reached the last four of a ranking event since 2006.
"I went 2-0 down and hadn't done too much wrong, then I made two centuries to get it to 2-2," said Williams.
"I'm just excited to be in the semi-finals. I haven't played [in Australia] for 20 years and it's been excellent to be back. Hopefully I can go all the way."
Doherty and Williams are second up on Saturday after the first semi-final between Shaun Murphy and Stuart Bingham.