Peter Uihlein turned in 33 to join the leaders midway through the third round of the True Thailand Classic Presented by Chang.
The American had set the early pace at Black Mountain Golf Club with an opening 64 on Thursday but a second-round 71 saw him enter the weekend three shots behind Scott Hend and Pelle Edberg.
But while the day's final pairing played their front nine in level par, Uihlein picked up shots on the first, seventh and ninth to join them at the top of the leaderboard on 12 under.
Thomas Pieters had made the big early move and was in the clubhouse at 11 under, with David Lipsky, Shaun Norris and Panuphol Pittayarat all a shot further back.
Uihlein is suffering with a wrist complaint but is currently in sparkling form and arrived at Black Mountain, a member of the network of European Tour Properties, on the back of two consecutive top tens.
Pittayarat was the first to join the leading duo at 12 under thanks to a birdie on the second but Hend had a gain on the same hole while Swede Edberg found the water to drop back.
The Thai then bogeyed the fourth to hand Hend a two-shot lead but the pack were gathering behind the 2014 Hong Kong Open champion.
Norris rolled in an enormous putt for eagle on the par five sixth and when Uihein made his second birdie of the day on the seventh, he joined the South African, Pieters, Edberg and Pittayarat in a five-way tie for second.
Australian Hend then found the sand with his second shot on the sixth and dropped a stroke after flying his third over the green, while playing partner Edberg had awkward lies off both his first and second shots but made a birdie to share the lead.
Uihlein made a third birdie of the day on the ninth to get himself into the leading group, shortly before Pieters parred the last to sign for a second consecutive 66.
The big-hitting Belgian had earlier made birdies on the first, second, seventh, tenth, 12th and 13th to vault himself into contention after missing his last two cuts.
Norris and Pittayarat then both bogeyed the ninth to drop to ten under alongside American Lipsky, who had a single birdie in his first ten holes on the sixth.
Frenchman Benjamin Hebert, Holland's Joost Luiten and Scot Simon Yates were all at nine under, with 16 players within four shots of the lead.
