Inbee Park took over the top spot in the women's golf ranking, ending Stacy Lewis' four-week run at No 1.
Park moved ahead of Lewis eight days after winning the Kraft Nabisco Championship for her second major title and second victory of the year.
The 24-year-old South Korean player also won the LPGA Thailand in February.
"This is a very big day in my golf career," Park said on Monday at the LPGA Lotte Championship in Hawaii.
"I'm so happy to share it with my family, who are here in Hawaii with me. It's nice to reach this goal, but I know a lot of players are close to No 1. It gives me something else to play for every week."
Lewis dropped to second, an average of 0.04 points per event behind Park in the two-year standings.
Taiwan's Yani Tseng remained No 3. She was No 1 for 109 weeks before Lewis grabbed the top spot with consecutive victories in Singapore and Phoenix.
Park is the eighth player and the second South Korean - following Jiyai Shin - to hold the No. 1 spot. Annika Sorenstam, Lorena Ochoa, Ai Miyazato and Cristie Kerr also have topped the ranking.
Last year, Park won twice on the LPGA Tour, had six runner-up finishes, topped the money list and took the Vare Trophy for lowest scoring average.
The putting star had a string of six straight top-three finishes. She won the Evian Masters in July in France, tied for third in her next start, added three straight second-place finishes and capped the run with a victory in October in the LPGA Malaysia.
Park won the 2008 US Women's Open and has five career LPGA Tour victories. She also has won four times on the Japan LPGA.
The LPGA Lotte Championship begins Wednesday at Ko Olina in Kapolei.
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