Charl Schwartzel dropped his first bogey of the week on Saturday but it would probably require a spectacular final round meltdown to deny the South African his maiden Thailand Golf Championship title.
The ninth-hole bogey was the lone blot in Schwartzel's penultimate round of four-under-par 68 as he raced five shots clear off Indian-born Swede Daniel Chopra at 18-under-par 198.
Chopra overcame a double bogey and battled to a 69 while local hope Thitiphun Chuayprakong scrambled to a 71 for third place further one shot back.
He dropped a double bogey on the par-five seventh hole to fall back but promised to give his best when he returns on Sunday.
"Obviously my goal is to go out and try to make it uncomfortable for Charl. Nobody wants to see him run away with it. I want to do my absolute best to make it close down the stretch," said the two-times winner on the PGA Tour.
Sergio Garcia sank two closing birdies in his round of 68 to lie eight shots off lead, a gap he thought too big to bridge.
"He played great last year and is doing great again," the Spaniard said of Schwartzel.
"He obviously likes the course. I like the course too but there are a couple of holes where I feel a little bit uncomfortable," Garcia said.
Westwood and Masters champion Bubba Watson shot 70 and 71 respectively for tied seventh place on 209.
Darren Clarke posted a third round 69 to lie in five un der in joint 18th position.