Scott Hend maintained his two-shot cushion at the top of the leaderboard as the leading players got their final rounds under way at the True Thailand Classic Presented by Chang.
The 43 year old is looking to become the fifth Australian to win on The European Tour this season and he got his round off to a steady start with a birdie on the second moving him to 15 under after three holes.
Big-hitting Belgian Thomas Pieters made a birdie-eagle start but dropped a shot on the third to sit two off the lead alongside American Peter Uihlein, who had a birdie on the third.
Local favourite Piya Swangarunporn was four under through seven holes to sit three shots back, one clear of Pelle Edberg, David Lipsky, Shaun Norris and Simon Yates.
Pieters used his enormous length off the tee to leave a short wedge in and birdie the first while another big-hitter in Norris joined him at 12 under as two mighty blows allowed him to eagle the par five second.
Yates had spoken this week of how putting had been his weakness over the years but he found his range quickly on Sunday, making birdies at the first, third and fourth to also move two off the lead.
That was not good enough to keep up with Pieters' early pace, however, as the two-time winner holed his bunker shot at the second to join Hend at the top of the leaderboard.
The 2014 Hong Kong Open champion soon moved back ahead with a birdie on the second, and the lead was back up to two when Pieters dropped a first shot in 39 holes on the third with a three-putt bogey.
Norris and Yates then made bogeys on the fourth and fifth holes respectively, while Lipsky had quietly gone about his business, picking up a shot on the second.
Swangarunporn had birdies on the second, fourth, sixth and seventh to move into contention.
Benjamin Hebert and Marc Warren were at ten under, with Prayad Markseang a shot further back having set the clubhouse target with a closing 66.