Rising Australian star Gabriela Ruffels has fallen a shot short as Nelly Korda regained women's golf's top ranking with another playoff victory at the Fir Hills Seri Pak Championship in California.

Korda edged out fellow American Ryaan O'Toole with a birdie on the first extra hole to claim back-to-back LPGA Tour victories for the first time in her career.

The 25-year-old also won the LPGA Drive On Championship in January in a playoff over Kiwi Lydia Ko.

Korda posted a two-under-par 69 at the Palos Verdes Golf Club on Monday (AEDT) while O'Toole's closing 66 also left her at nine under through 72 holes.

"I'm aging myself really quickly out here," Korda said.

"The weekend was brutal. It's also the beauty of the game. It's fun to be able to play in these conditions and be a little more artistic."

Playing in only her third LPGA Tour event, Ruffels needed a birdie at the last to force a three-way playoff, but left her 20-foot attempt short after Korda finished bogey, bogey to invite her chasers in.

The 23-year-old had held a share of the lead following three birdies in four holes heading to the ninth tee.

But a double-bogey six on the par-4 ninth ultimately cost Ruffels the biggest win of her career.

"It was such a special week considering that on the back nine on Friday I was outside the cut line," Ruffels said.

"I had a really good weekend and managed the wind.

"Standing over the putt (on 18) I realised that was to get into a playoff ... It's really cool to be in that situation. Unfortunately didn't make the putt but I thought I hit a pretty good putt.

"It was such a special week to be here at Palos Verdes with my family close by and to kind of have my best result in an LPGA event.

"My mum grew up in this area and my whole extended family was out here ... having that support just really carried me through today."

She signed for a final-round 70 to share fourth with American Alison Lee (70) as Korda celebrated her 10th LPGA Tour win.

The former Australian Open champion is the first player to salute in back-to-back starts since Frenchwoman Celine Boutier won the 2023 Amundi Evian Championship and the Women's Scottish Open.

Korda will return to world No.1 for the sixth time - and first time since last August - after supplanting compatriot Lilia Vu from top spot.

With AP.