At 15-under 195, Choi leads Tim Wilkinson by four shots. A rookie from New Zealand, Wilkinson vaulted into contention with an eight-under 62 to get to 11-under 199.

Na had an uneven round with four birdies and three bogeys, but he did birdie 18 for a 69 and is tied for third at 10-under with Steve Marino (68).

Choi wasted no time building on his lead as he birdied his first two holes. But he was unable to capitalise on that early momentum and had only three more birdies the rest of the round.

“I started out with birdies and felt like I was going to have a very good day,” Choi said. “During the middle of the round I faced a lot of difficult pin positions so it made it a little bit difficult.”

After closing the front nine with a birdie, Choi bogeyed number 11.

He picked up a shot with a birdie at 14 and closed his round with a birdie at the par-five 18th after blasting out of a greenside bunker to about six feet.

Looking for his seventh PGA Tour win and a wire-to-wire victory this week, Choi has fired three rounds in the 60s and will be tough to catch on Sunday.

“I’m very satisfied with my shots, the way I’m shaping my shots,” Choi said. “I’m hitting the shots the way I want to and I feel really good about my shots. I feel like I had a good round.”