JEJU ISLAND, South Korea -- Brooks Koepka has improved his chances of taking over as No. 1 golfer in the world, shooting a bogey-free 5-under 67 Saturday for a four-stroke lead after three rounds of the CJ Cup at Nine Bridges.
The 28-year-old Koepka, who trailed by one stroke after two rounds, will move to the top of the world rankings if he wins the tournament and former No. 1 Justin Thomas, the defending champion here, does not finish any better than second.
Thomas shot a 71 Saturday and is at 1 under, 12 strokes behind Koepka and tied for 43rd. It would be Koepka's first appearance at No. 1.
Shubhankar Sharma of India had the round of the day, a 64, to move to 3 under, 10 strokes behind Koepka.
Koepka, the three-time major champion who was recently voted the Player of the Year on the PGA Tour, started with eight straight pars.
His round included back-to-back birdies on the ninth and 10th holes, and then a key par save from a difficult lie in the greenside bunker on the 11th -- the only hole where he looked in any kind of trouble.
"It was good on the 11th, just to make sure I didn't have any bogeys, that was kind of the big thing," Koepka said. "I unfortunately three-putted the next (par-5 12th). Just got to work on my wedge game, which wasn't very good today."
Looking ahead to the final round, he added: "My confidence has always been pretty high. Anytime you can win three majors you're going to be feeling pretty good about yourself. To do what I've done over the last two years has been special, but I'm looking to build on that."
After a round of five birdies and a bogey, Poulter also knew what he needed to do on Sunday.
"Tomorrow, I think it's not as windy as Thursday, so with that in mind, I think the scoring's going to be pretty good," said Poulter, who has improved to No. 35 in the rankings after coming close to losing his card on the PGA Tour in 2016.
"Tomorrow, I'm going to need to make a few birdies. Obviously, Brooks is in cruise control right now and obviously I am going to need a shoot a low one."
Piercy, looking for his first individual win on the PGA Tour since the Barbasol Championship in July 2015, started with a birdie, but needed to make birdies on his last two holes to ensure he finished on even-par.
"I'm a little frustrated. I felt I rolled the ball really well today and I kept hitting lip after lip. A couple mistakes like hitting it in the cross bunker on the sixth.just a little sloppy and the ball-striking wasn't quite there," said Piercy. "Just made stupid little mental errors today and it's hard to come back from it."
The $9.5 million tournament is the second in the PGA Tour's three-week Asian swing culminating in the WGC-HSBC Champions next week in Shanghai.