American Han Lee surrendered his overnight lead after picking up just three points on the rain-soaked day at the second round of The Players for The Players golf tournament in Gunma.
The 45-year-old, chasing his first JGTO victory in 10 years, mixed three birdies with as many bogeys at The Raysum to reach the halfway stage on 17 points - four behind leader Daiki Imano in the inaugural tournament which uses the Stableford scoring format.
Players receive eight points for albatross, five for eagle and two for birdie. A point is deducted for a bogey and three is taken away for a double bogey or worse.
Philippines' Justin De Los Santos was the other big-moving international member of the day, moving up 13 places to tied-11th alongside South Korea's Hyunwoo Ryu, after scoring six points to bring his tally to 12.
Australian duo Anthony Quayle and Matthew Griffin signed for nine points and two points respectively to be tied for 16th and 31st, while reigning JGTO Money Ranking winner Chan Kim sits joint-48th and 15 points off the pace.
Michael Hendry of New Zealand and Australia’s Andrew Evans made the cut on five points.
Lee was glad to have survived the wet and cold conditions which he admitted he struggled to cope with.
"It's really hard out there today," said Lee, who last tasted success back in 2012 at the Taheiyo Masters.
"We were quite lucky to tee off without rain (earlier the day). After that, it was getting harder and harder.
"You just got to accept that it's going to be hard today, so you got to be really patient. There are going to be bogeys today, if you get a couple of looks for birdie, you got to capitalise them.
"Hopefully the weather gets better, I would love to see the sun soon!"
As brutal as the wet conditions were, De Los Santos had no complaints about it and said that it was something that all players had to deal with.
De Los Santos was also amazed by the fact that the course wasn't badly impacted by the heavy rain.
"It was a pretty wet day, it certainly wasn't the most fun thing," said the 26-year-old.
"I was just trying to make sure everything's pretty dry and make sure the ball stays up in the air.
"Even with the weather, the course is in good shape and holds up really well. The greens have not flooded at all."
De Los Santos hopes to continue charging up the leaderboard by capitalising on the unorthodox scoring system, which was brought back on JGTO after a lapse of 24 years.
"I have never competed in a Stableford event at all," he explained.
"It's a little bit different, but I like it a lot because I can be more aggressive."
Imano raked in 13 points courtesy of eight birdies and three bogeys for a two-day total of 21 points to lead by one from Shintaro Kobayashi.
"Looking back at today’s round, the bogey on the first hole was a result of misjudgement. It was a waste really," he said.
"But there were good par saves too. All in all, it's still a great round.
"Now that I'm at the top, I want to try to keep this position and win this week," said the Japanese leader.