It is Thompson’s highest ranking in her eight-year professional career.
Ryu’s reign at No. 1 has reached six consecutive weeks.
Former world No. 1s Ariya Jutanugarn and Lydia Ko both slipped another spot in the rankings this week. Jutanugarn, who is the defending champion at this week’s Ricoh Women’s British Open, slipped down to No. 3. Ko moved down to No. 5.
Ryu and Thompson have been setting the pace on tour since their playoff battle at the year’s first major championship, the ANA Inspiration, where Ryu won on the first extra hole. They are also 1-2 in the Rolex Player of the Year race with Ryu out front.
Thompson leads the tour in scoring with a 68.94 average. Annika Sorenstam is the only player in LPGA history to end a year with a scoring average below 69. Sorenstam did it twice, setting the tour record with a 68.6970 mark in 2004.