Kiradech Aphibarnrat produced a stunning birdie on the shootout hole to set up a final against James Nitties at the ISPS HANDA World Super 6 Perth.
The Thai only entered this event seven days ago and arrived having not played any practice rounds at Karrinyup Country Club.
He was the last man into the knockout on Saturday after playing the last four times in a play-off and was looking to emulate countryman Phachara Khongwatmai, who made the final last year after being the last man to qualify.
He was one down with one to play in his semi-final against Lucas Herbert but the Australian made a bogey and when Aphibarnrat put his tee-shot to two feet on the shootout hole, it was all over.
Australian Nitties was a 2 and 1 winner over Sam Horsfield in the other semi-final.
The players are facing off against each other over the tenth, 11th, 13th, 14th, 12th and 18th, with the 90-yard shootout hole used to separate those still all square.
After victories over Ben Eccles, Yusaku Miyazato and Sean Crocker, Aphibarnrat put his approach to the first close, with Herbert duffing his second into the sand and failing to get up and down to concede the hole.
The second was halved in pars as was the third, with both men making impressive recoveries after sending their tee-shots a long way right off the tee.
Aphibarnrat found the sand off the tee on the driveable next and with Herbert leaving himself six feet for eagle, they were all square heading to the fifth.
Herbert made it back-to-back twos on the par three next with a 12-foot putt down the hill and he had the advantage on the sixth tee.
He bogeyed after going over the back of the green and the duo headed to the shootout tee, with Aphibarnrat saving his best for last as he hit into the 18th green for the 17th time this week.
Horsfield came through all three stages to win the Qualifying School in November but has missed three of his four cuts in 2018 as he finds his feet on the European Tour.
The Englishman has looked like a veteran performer this week, finishing in the top eight after the stroke play to earn a bye into round two of the match play and then beating Matthew Millar and Min Woo Lee to guarantee his best finish.
Nitties is also assured his best European Tour result after victories over Nick Cullen, Dimitrios Papadatos and Callan O'Reilly, with one top ten in his previous 24 appearances.
Horsfield came up short of the first green and failed to get up and down as he surrendered the hole.
He was in the driving seat on the second but Nitties holed a 15-footer for birdie and with Horsfield failing to get up and down from a greenside bunker, the home favourite was in command.
The third was halved in pars and the fourth in birdies after Nitties got a fortunate bounce out of the trees off the tee and Horsfield made a smart right-to-left putt.
The 21 year old also birdied the fifth but Nitties was inside him off the tee and made a birdie of his own to seal victory.
