Moriya Jutanugarn climbed nine places to No.23 in the latest world rankings after her joint-third finish at the Evian Championship on Sunday.
World No.23 Moriya Jutanugarn. ap Darron Cummings
Her younger sister Ariya, meanwhile, dropped one place to No.5 after missing the cut at the Evian event.
Moriya, 23, came close to winning her first LPGA title at the Evian which was reduced to three rounds due to bad weather.
She was leader after two rounds and held a three-shot advantage after 12 holes in the final round. But a wayward shot at the 13th saw her drop to one stroke behind eventual champion Anna Nordqvist.
Moriya would have joined Nordqvist and Brittany Altomare in a play-off with a par at the final hole but she suffered a bogey.
Moriya, Lydia Ko and Katherine Kirk finished one shot behind the leading duo.
Ariya, 21, took over the No.1 ranking after winning the Manulife Classic in June. But she has since faltered and missed the cut in four successive majors.