Philadelphia, PA (Sports Network) - Cristie Kerr became the first American woman ranked No. 1 in the world following her 12-shot win Sunday at the LPGA Championship.

By picking up her second career major with a record-setting performance at Locust Hill, Kerr moved past Japan's Ai Miyazato to become just the fifth player overall to hold the No. 1 spot since the world rankings for women's golf were instituted in 2006.

Sweden's Annika Sorenstam and Mexico's Lorena Ochoa held sway over the rankings for more than four years, but their retirements have left the No. 1 spot open for attack.

Since Ochoa stepped away in May, three women have held the top spot: South Korea's Jiyai Shin, Miyazato and now Kerr.

"It means a tremendous amount. It's something that I've wanted my whole life, I worked for my whole life," Kerr, 32, said on Sunday. "It's great to be No. 1, but I just got there. To be No. 1, I feel in my heart you really have to keep proving it. So I got a lot of work ahead of me."

Kerr replaced Miyazato, who was No. 1 for only a week after capturing her fourth win of the season at the ShopRite LPGA Classic on June 20.

Miyazato needed a solo runner-up finish at the LPGA Championship to keep the No. 1 ranking -- although she didn't know that. She played great anyway, shooting a six-under 66 in the final round to tie for third place.

The 25-year-old Japanese star slipped just .12 average points behind Kerr and into the No. 2 position. By comparison, Miyazato leads No. 3 Shin by .76 points.

"Even if [it was] just for one week I was able to get experience, and I will take very many positive things out of it," Miyazato said of her stint atop the rankings.

Kerr moved up four places from her No. 5 ranking last week, dropping Miyazato, Shin, Suzann Pettersen and Yani Tseng down one spot apiece to complete the new-look top five.