The 21-year-old from Taiwan shot her second consecutive 4-under 68 on Friday, taking a four-shot lead after the second round of the Women's British Open. The American duo of Brittany Lincicome and Christie Kerr joined Amy Young of South Korea in the chase entering the weekend.
"There was no wind this morning and it was very calm, so it was nice out there," said Tseng, who is trying to win her third major championship. "The course played totally different than what we played the last three days, so it was really nice."
Rain washed over Royal Birkdale in the afternoon, making things difficult for the late starters -- including defending champion Catriona Matthew of Scotland, who missed the cut by seven strokes after making a 10 at the par-four 13th hole.
Her tee shot landed in a bush, and she eventually found the deep rough near the green. After three tries to hack her way out of it, Matthew ended up taking a penalty drop, chipping onto the green and two-putting for her 10 -- only to birdie the par 3 next hole.
"After the 10 I just wanted to get in," said Matthew, whose 10-2 sequence on her scorecard was part of a 9-over 81. She missed the cut at 12 over.
Kerr certainly didn't have any problems, posting the low round for the tournament with a 5-under 67. She made a pair of 10-footers for birdie on the first two holes, dropped a stroke at the eighth, then picked up four more birdies to join Lincicome and Young at 4 under.
"I played really well today," Kerr said. "I was determined to be more relaxed out there. I've been putting a lot of pressure on myself since getting the No. 1 ranking and I hadn't really realized that's what was going on. So I just went out and did my thing today."
Lincicome had a birdie at the second, then dropped four strokes in a three-hole stretch beginning at the 11th. She also took advantage of an easy finish at Royal Birkdale, though, with a birdie at No. 15, an eagle two holes later and another birdie at 18 for her 1-under 71.
Veteran Julie Inkster also shot herself into contention with a 2-under 70 that left her five shots off the lead, doing so in the worst of the weather. Suzann Pettersen of Norway shot a 68 and Sun Young Yoo of South Korea had an even-par 72 to join Inkster in a tie for fifth.
"It was rainy and tedious but I was very happy with the way I played," said the 50-year-old Inkster, who bogeyed the third hole but recovered with a birdie at the fourth. She picked up two more birdies at the 15th and 17th to finish her round with some momentum.
"There's a lot of good names up there but we're all going to be playing at the same time tomorrow," Inkster said, "so that's going to help."
Michelle Wie failed to take advantage of an early start time, hitting her first tee shot out of bounds. She ended up shooting a 4-over 76 that left her 10 strokes off the lead.
Fellow American Christina Kim went the other direction with a 4-under 68 that moved her into a tie at 2 under. She's joined by Frenchwoman Anne-Lise Caudal (73), Japan's Momoko Ueda (70), first-round leader Katherine Hull (74), and South Koreans In-Kyung Kim (72), Hee Kyung Seo (69), M.J. Hur (68) and Jiyai Shin (71).
"There was no wind when we started, so I said to myself that I've got to take advantage of the conditions," said Kerr, who won the LPGA Championship by 12 shots earlier this season.
"The last time I was here at Birkdale (in 2005), I got the wrong end of the split," Kerr said. "I had the worst of the weather in both the first and second rounds, but this time it has been different, so I knew I had a chance to do well."
Kerr and the rest of the field will still have to chase down Tseng, who has already won the LPGA Championship and Kraft Nabisco Championship in her brief professional career.
The precocious young player made five birdies on Friday and dropped her only shot on the 373-yard par-4 third, when she drove into the bunker on the left side of the fairway and failed to reach the green in regulation for the first time in 21 holes.
"I played another solid round and made a lot of putts," said Tseng, who had three birdies over the final five holes. "I have never led a major from the start before, but I feel confident and believe I can continue to play well."