Fifteen players were separated by just four shots at the top of the leaderboard as Belgium's Thomas Pieters continued his bid for an unlikely third European Tour title in the True Thailand Classic.
Pieters, who won on consecutive appearances in the Czech Masters and KLM Open last year, was nine shots off the lead - and three outside the cut - following an opening 73 at Black Mountain Golf Club.
However, the 24-year-old then carded a 66 in the second round on Friday and followed it with another on Saturday to set the early clubhouse target on 11 under par, just one behind joint overnight leaders Pelle Edberg and Scott Hend.
Pieters, who would secure his place in next week's WGC-Dell Match Play with a good finish in Hua Hin, made the ideal start with birdies on the first and second before picking up another shot on the seventh to reach the turn in 33.
The world number 66 then birdied the 10th, 12th and 13th but could be left to rue missing further good opportunities on the last two holes as he waited to see what the later starters could achieve.
Hend had briefly enjoyed a two-shot lead when he birdied the second and playing partner Edberg bogeyed after finding water with his approach, but the roles were reversed on the sixth when the Australian thinned a bunker shot across the green.
American Peter Uihlein made it a three-way tie for the lead with his third birdie of the day on the ninth, but missed from five feet for birdie on the 11th and dropped a shot on the 12th after firing his approach over the green.