Stacy Lewis won her seventh LPGA Tour title on Sunday and that helped her jump to the No. 1 spot in this week's women's world rankings.
Lewis joined Cristie Kerr as the only two Americans to top the women's rankings, which started at the beginning of the 2006 season.
Lewis's move bumped former No. 1 Yani Tseng down to second and Na Yeon Choi down to third.
Inbee Park, Shanshan Feng and Jiyai Shin remained in the fourth through sixth positions. Ai Miyazato led entering the final round of the RR Donnelley LPGA Founders Cup, but fell to second place after a double-bogey at the 16th. She nonetheless improved two places to seventh.
Suzann Pettersen and So Yeon Ryu both dipped a notch to eighth and ninth. Mika Miyazato held steady at No. 10 and was again followed by Paula Creamer, Cristie Kerr and Catriona Matthew.
Amy Yang and Karrie Webb exchanged places with Yang up to 14th. Azahara Munoz stayed put at No. 16 and was followed by Angela Stanford, who climbed two spots, Sun Ju Ahn, who slipped one, and Mi-Jeong Jang, who improved a pair.
Brittany Lincicome dropped two spots to 20th, while last week's 20th-ranked player Lexi Thompson fell three to 23 this week.