Perth - Overnight leaders Brett Rumford and Lee Westwood crashed out of the $1.75 million Handa Super 6 tournament in Perth on Saturday.
On a dramatic day during which strong prevailing winds played havoc with the field, seven different players held the lead at different stages.
When the dust settled, little-known Thai journeyman Prom Meesawat, nicknamed "The Big Dolphin" because of his penchant for swimming, had topped qualifying at 12 under after shooting 67 in the third round.
He was followed by three players at 10 under -- big-hitting young Australian Lucas Herbert, American Sean Crocker and Denmark's Thorbjorn Olesen, who won in Perth in 2014.
All of the top four held the lead at some point during the day, but nonetheless start on a level footing on the final day.
The unique tri-sanctioned European Tour tournament sees the top 24 after the first three rounds of strokeplay undertake matchplay on the final day to decide the winner, with the top eight qualifiers having a bye in the first round on Sunday.
Having been the top two after both of the opening two rounds, Westwood and Rumford suffered a stunning demise to miss the last 24, leaving the tournament without any of its marquee players on the final day.
Starting the day joint leaders at eight under, Westwood and Rumford had horrendous rounds, both shooting 78 as they tumbled down the leaderboard to finish equal 40th at two under.
Former world number one Westwood struggled all day with wayward driving and heaved his club in frustration after teeing off into the bush on the 14th.
He scrambled out of that with a par, only to double bogey the next hole to drop to two under and slip out of contention.
"Not a lot went my way," Westwood said. "I hit a few bad shots, got a few bad breaks, never made any putts. I made one birdie on the 17th, so you're not going to score well doing that."
Rumford was the defending champion, having won the qualifying stage by five strokes last year.
He looked well placed to reach the final 24 until a disastrous double bogey on the 16th killed off his chances.
"It was a tough day, a long day," Rumford said. "I felt like I hit it alright, but my short game wasn't at its usual level and it was just a flat round."
After the third round was completed, nine players who were tied for 17th had to partake in a playoff to decide the field for the final day.
Meesawat produced seven birdies and two bogeys to move into a position to notch his first European Tour win, which would secure his card on that tour.
His best previous result on the European Tour was a playoff loss to Miguel Angel Jimenez and Stuart Manley in Hong Kong in 2013.
Although he said he believed his last experience of matchplay was at least a decade ago, the 33-year-old was excited by the opportunity to participate in the final day.
"I have been playing good the last two days, so hopefully I can keep that going tomorrow," Meesawat said. "It's going to be good fun."