Choi recorded a total of nine birdies and just one dropped shot, on the par-four third, before lightning caused play to be suspended.

Australian Rod Pampling carded a six-under round told hold second place in the clubhouse, while Billy Andrade and Bart Bryant, who still has the 18th to play, were a further stroke back.

Choi, who has already won on the PGA Tour this season - the Compaq Classic in May, said afterwards: "I just came back from Korea and wasn't expecting to play well with jet lag.

"But the course was very tight with narrow fairways and I was driving very well and my iron shots were very good.

"Putting was the only thing I had a doubt with but I worked in the morning on the putting green and was making everything today."

Choi insisted he was relieved to have recaptured his best form.

Since winning in New Orleans, he has struggled to figure highly on the leaderboard.

He explained: "After the first win...I maybe relaxed too much.

"I was treated like a champion. It took almost two months to get used to it. Now I'm out of a little bit of a slump."

Pampling was the early leader following his 65, in which he also recorded a single dropped shot on the third.

But he remained confident of reeling in Choi.

"K J had a great day out there." he said. "Fortunately, things also went my way too and I'm not far behind."

The 18-year-old Ty Tryon finished with a round of 73 in his first PGA Tour start since March.

Tryon, the youngest player to earn a PGA Tour card, had four birdies and five bogeys in a mixed round.

The American teenager said: "I'm just excited to be out here. I felt like a regular pro."