World number three Ariya Jutanugarn had to go the distance to dispatch her elder sister Moriya 2 up on Friday in the second round of the LPGA Lorena Ochoa Match Play.
Ariya, the 21-year-old seeded first in her bracket, never trailed her 22-year-old sister, but never stretched her lead beyond two holes in their first match play meeting as professionals.
"Today we had fun because we are sisters, and we always have fun anyways," said Ariya, who carded four birdies to Moriya's two.
"She plays so good, I can?t believe I beat her today because she?s so good."
Although they said the rare head-to-head clash was "weird" they didn't find it stressful.
There was a bit of sibling taunting -- Moriya told Ariya prior to the match she would insist her younger sister putt out at every hole, while Ariya threatened to slow her pace of play.
Moriya, ranked 53rd in the world, took her sister to the 18th, where Ariya made a 20-foot birdie putt to seal the win.
"We always say, just have a good day," Moriya said. "We know that we both are going to try our best, play our games.
"Hopefully next time we are not in the same pool and don't have to see each other so early in the week."
Ariya advanced to a meeting with Sweden's Pernilla Lindberg, a 4 & 3 winner over American Brittany Lang.
Lindberg beat an up-and-coming Ariya in singles play in the 2014 International Crown -- before the Thai had claimed any of her five LPGA titles.
"Obviously she has had a lot of success since then, so I will be the underdog," Lindberg said.
As Ariya moved on, so did world number one Lydia Ko, ensuring that her Thai rival can't replace her atop the world rankings this week.
New Zealand's Ko defeated American Jennifer Song 1 up. Ko took the lead with an eagle at the par-five second hole, but the American responded with birdies to win the seventh and 10th.
Back to back birdies at 11 and 12 had Ko in front again, but they were back to all-square when Ko bogeyed the 14th. Ko responded with a birdie to win the 15th, regaining a lead she wouldn't relinquish.
She'll next face South Korean Hur Mi-Jung, who needed 20 holes to beat Norway's Suzann Pettersen.
China's Feng Shanshan also worked overtime, beating Australian Sarah Jane Smith in 24 holes.
- Stanford ousts Park -
South Korean Park In-Bee became the second player seeded number one in a bracket to fall as Angela Stanford bounced the seven-time major champion 3 & 2.
Park took a 1 up lead when Stanford bogeyed the fourth hole, but the American squared the match with a birdie at the seventh and steamed to a 3 up lead through 14 with three birdies in four holes.
"I think, when playing someone like her you just know that you can't make mistakes," Stanford said. "I made one on hole four and I remember telling my caddie 'the only way I'm going to beat her is with birdies.'"
Stanford next faces France's Karine Icher, who beat Spain's Carlota Ciganda in 21 holes.
© 2017 AFP