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Yani Tseng continued her run toward a fifth under 67 Saturday in the second round of the Walmart NW Arkansas Championship.

Tseng, the defending champion and top player in the world, finished 36 holes at nine-under 133 and is looking for her 10th career title at Pinnacle Country Club, the site of her fifth career win in 2010. She had six birdies and two bogeys on Saturday, but played her closing nine flawlessly to remain atop the leaderboard.

This is the eighth 36-hole lead for Tseng, who has gone on to win in the last two instances.

"I think it's hard to not have pressure because ... (I'm the) defending champion and in the lead," Tseng said. "I just want to enjoy the pressure. I know tomorrow, first couple holes (I'm) going to be nervous. If I were not nervous, that would be a little weird ... I'll try to stay as relaxed as I can and maybe sing a song in my mind and just look around and enjoy the crowd tomorrow."

She shares the honors with Amy Yang, whose seven-under 64 helped her climb all the way to the top. Yang had an eagle to go with six birdies and a bogey in her sensational round.

Yang is not quite as accomplished as Tseng, but still has three LPGA Tour victories, with the last coming in 2008. She has only four top-10 finishes this year, but has missed her last two cuts after making the final round in each of her first 13 events of 2011.

It's only the second 36-hole lead for Yang, who finished second at the LPGA Tour Championship in 2010 after leading following the second round.

"Everything was good today," Yang said. "I was hitting the ball solid and hitting the putts solid. You know, from tee to green, I was playing good. I'm really happy about my game."

American Taylor Leon is one stroke behind at minus-eight after a four-under 67 and is in search of her first win since 2007.

Cristie Kerr (66) headlines a group that shares fourth at seven-under 135 along with Inbee Park (65), Jin Young Pak (68) and Stacy Lewis (69). Former world No. 1 Ai Miyazato (67) is at minus-six with Belen Mozo (65), Morgan Pressel (68) and Paula Creamer (68).

Tseng began on the back nine Saturday and didn't get off to a great start.

After a birdie on No. 11 put her at six-under, she bogeyed the 14th and 16th surrounding a birdie on the 15th to fall back to minus-five. Tseng made the turn at that mark, but took off on her final nine.

Tseng birdied the first two holes on the course to begin the back nine and move to seven-under, and she continued her flawless finish with birdies on the fifth and seventh to move atop the leaderboard.

Two final pars helped her maintain the lead.

"I worked on my tempo on the back nine," Tseng said. "I got a little too fast with my tempo, but I just keep to myself, keep focused and actually (on the) back nine I got really lucky."

Yang also began on the 10th tee, started strong and finished even stronger.

She moved to five-under within five holes of starting her round with three birdies. Like Tseng, Yang made the turn at five-under and moved to six-under with birdies on the third and fifth around her lone bogey of the day at No. 4.

On the seventh, Yang posted an eagle and followed with her final birdie of the day at the eighth to get to nine-under.

NOTES: The cut fell at two-over 144, with 80 players advancing to the final round...Sara Brown, a contestant on Golf Channel's "Big Break," made the cut for the first time on an LPGA Tour event. She's tied for 11th at five- under...Karrie Webb made the cut on the number after a birdie at No. 18. She has not missed a cut all year, and her last missed cut came at this event in 2010.