An unpredictable LPGA season careers into Trump National with no clear favourite for the most prized trophy and richest event in women's golf at the US Open.
As organisers wondered whether US President Donald Trump will show up at his course to soak in the major championship atmosphere, handicappers struggled to pinpoint who will emerge among contenders at the $US5 million ($A6.5 million) event beginning Thursday.
So Yeon Ryu, Ariya Jutanugarn and Lydia Ko took turns as No.1 in the world rankings over a period of four weeks in June, while 15 different players cashed the winner's cheque at the first 15 LPGA Tour events for the first time in 26 years.
Lexi Thompson is ranked No.3, ahead of Ko, with Chun In-gee of South Korea, the 2015 champion, at No.5.
"The girls that are one, two, three right now, they're playing such amazing golf and you can see that we've had 17 different winners out of the 18 events and just shows the amount of talent on the LPGA right now," said fourth-ranked Ko.
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Ariya ended the 85-week reign at No.1 by Ko after winning a three-way playoff against Thompson and Chun at the Manulife LPGA Classic on June 12.
Two weeks later South Korean Ryu leap-frogged the Thai into top spot by winning the Walmart NW Arkansas Championship and becoming the season's first multiple winner.
A different wrangle placed a cloud over the occasion as the choice of Trump National to host the event, made before Trump announced his candidacy, angered women's activists because of controversial comments on women he made during his campaign.
The 156-player field will be grappling with a layout routed through the property's 500 acres of rolling hills and pasture land where former owner automaker John DeLorean once raised a herd of cattle.
