Thailand’s Pornanong Phatlum fired a six-under par 66 on Friday to maintain a one-stroke lead at the halfway stage of the US LPGA Safeway Classic.

Pornanong’s two day total of 14-under 130 broke the previous 36-hole tournament record at Columbia Edgewater Country Club and left her one stroke in front of Norway’s Suzann Pettersen, who carded a nine-under 63 for 131.

Pettersen jumped from a tie for 20th to second place, one shot in front of Germany’s Sandra Gal who notched her second straight 66. German rookie Caroline Masson was alone in fourth on 133 after a second-round 64.

Karrie Webb was the best placed Australian at 8-under, six shots off the pace.

Pornanong, who won the unofficial HSBC Brasil Cup last year, holds the 36-hole lead for the first time as she seeks her first official win in five years on the LPGA Tour.

The 23-year-old had six birdies without a bogey.

“I played this good before, but this is the first tournament that I felt really good and really confident, so I’ve played really good, better than I have done before,” she said. “I’m more confident and everything is better than I have before.”

Although she has yet to win on the LPGA Tour, Pornanong has seven professional victories on the Ladies Asian Golf Tour and Ladies European Tour.

Pettersen made her big move with a round that featured nine birdies without a bogey. She birdied five of her first nine holes and said her putter was key.

“It was a great round on the greens,” Pettersen said, adding that she benefited from her pairing with European Solheim Cup teammate Beatriz Recari.

“I kind of fed off Beatriz’s start,” Pettersen said. “She had five pretty quick birdies. It was kind of nice to get everyone going early… I pretty much made every good look that I had. One of my better putting performances here.”

Masson, who is chasing Moriya Jutanugarn for the LPGA’s Rookie of the Year Award, can pass the Thai player with a finish of 19th or better. Moriya missed the cut after rounds of 73-71.

Masson, however, said she wasn’t focusing on the award.

“I’ve been happy with my season so far,” she said. “I kind of did everything I wanted to. I played Solheim and I kept my card… There’s no pressure for me really. I can only surprise, I guess, and that’s my goal for the next two days is to keep doing what I’m doing right now, just have fun.”