Pat Perez took control of the CIMB Classic after moving four shots clear of Xander Schauffele following Saturday's penultimate round.
Perez held a slender one-stroke lead over PGA Tour Rookie of the Year Schauffele at the halfway stage of the tournament in Kuala Lumpur.
But the two-time winner on Tour gave himself breathing space atop the leaderboard thanks to an eight-under-par 64.
Perez had nine birdies, including six on the way home, for his lowest round of the event and a third successive day in the 60s to be 21 under overall.
Tour Championship winner Schauffele carded a third-round 67 on Saturday.
Enjoying a breakout year with two titles and fifth place at the U.S. Open, Schauffele stayed second thanks to a flawless back nine, having posted an eagle and a pair of birdies.
A shot further back is Kang Sung following his 65, while Hideki Matsuyama (63) and Keegan Bradley (65) are 15 under through 54 holes.
Defending champion and FedEx Cup winner Justin Thomas, meanwhile is 15 shots off the pace heading into Sunday's final round.
After rounds of 70 and 71, in-form Thomas broke into the 60s for the first time this week via a three-under-par 69 but the American has a mountain to climb if he is to achieve a three-peat.