American Brittany Altomare rallied to beat top-seeded Minjee Lee 2&1 on Thursday in round-robin play at the LPGA Match-Play at Shadow Creek in Las Vegas, Nevada.
Australia's world number four Lee, who arrived in Nevada fresh off a victory in the Founders Cup, was 3-up through seven holes, but she couldn't make a birdie on the back nine as Altomare, a US Solheim Cup player, roared back.
Altomare won five of seven holes to take a 2-up lead through 14 that she wouldn't relinquish.
"Minjee's such a great player, I knew I had to be on my game today," Altomare said. "I was a little bit disappointed with the way I started out, but I've learned in Solheim you just never know what's going to happen in a match.
"You've just got to stay patient and play your game."
Altomare said a solid shot out of a fairway bunker at the sixth boosted her confidence, and even though Lee responded with a birdie to win the seventh, she felt that was a turning point.
"I started feeling good after that," she said.
Hong Kong's Tiffany Chan, ranked 63rd in the 64-strong field and playing on a sponsor's invite, notched her second straight victory.
After beating second seeded Thai Atthaya Thitikul on Thursday, she beat "good friend" Alison Lee of the United States 4&3.
In a match that went "back and forth, back and forth," Chan said, a few birdies were the difference.
"In the end I got more lucky, had a couple more putts," said the Las Vegas resident, who said the hot, windy conditions and firm course took her a bit by surprise.
"A lot of the game plan has to change," she said.
Thitikul suffered a second straight defeat, falling 1-up to American Amy Olson.
Defending champion Ally Ewing bounced back from an opening-day defeat with a 3&2 victory over Thailand's Jasmine Suwannapura, but last year's runner-up Sophia Popov dropped a second straight.
South Korea's Kang Hae-ji rallied from an early deficit to beat Germany's Popov 2-up, winning four of the last six holes.
Ewing took a 2-up lead through five holes and never trailed from there.
"I definitely feel like today versus yesterday I was able to convert some birdies early on and have some good looks," said Ewing, who said a "very unexpected" par to win the eighth -- with a 35-foot putt -- was another big boost.