NEW YORK - Lydia Ko's reign as world No 1 is set to end this weekend, but it remains unclear just who will replace her at the summit after the conclusion of the LPGA ShopRite Classic on Sunday.

According to LPGA projections, either South Korean Ryu So-yeon or Thailand's Ariya Jutanugarn will be the new No 1 on Monday.

The two have been closing in on New Zealand's Ko for weeks, and Ryu is in the driving seat this week as the only player in the trio teeing it up at the Stockton Seaview Hotel and Golf Club near Atlantic City, New Jersey.

Ryu, currently ranked third in the world, can leapfrog world No 2 Ariya to seize top spot if she finishes third or better - although a tie for second or third could open the door for Jutanugarn.

If Ryu is fourth or worse, Ariya will rise to No 1, the LPGA has projected.

"Since I dreamed about the LPGA tour I also dreamed about becoming the number one player in the world," Ryu said this week as she prepared for Friday's opening round.

"I definitely want to become number one at some point, and I'm working really hard for that as well.

"But I think the more important thing is to enjoy this moment and enjoy playing golf. I believe that will get me to number one."

South Korea-born Ko, 20, has topped the rankings for 84 straight weeks and 103 weeks overall.

Ryu thrust herself into the race for top spot with a victory in the year's first major, the ANA Inspiration at Mission Hills in California. The 26-year-old's victory came after American Lexi Thompson was controversially penalized during the final round for an infraction on the previous day.

Agence France-presse