Defending champion Nozomi Okuhara surrendered her women's singles title in the USD300,000 Yonex Japan Open title in the quarter-finals as compatriot Akane Yamaguchi ended her reign with a 21-11, 23-21 win.
The Tokyo Metropolitan Gymnasium will be long remembered by sixth seeded and world No 12 Akane as she ended her six match win-less run against second seed Nozomi, ranked world No 5.
Akane's last defeat at the hands of her more illustrious compatriot was at the Rio Olympics where Nozomi won the quarter-final tie 11-21, 21-17, 21-10.
Nozomi, who is the reigning All-England Champion and winner of the Dubai World Superseries last year, went on to take the bronze medal in Rio.
In last year's Japan Open final Nozomi triumphed 21-18, 21-12 as Akane took a giant step towards coming out of the shadows of Nozomi.
Friday's win is a big breakthrough for Akane – twice voted BWF's Most Promising Player of the Year – in 2013 and 2014.
The 19-year-old Akane will face China's seventh seed Sun Yu for a place in the final. The lanky Chinese ran out an easy 21-14, 21-9 winner over homester Sayaka Takahashi in 37 minutes.
Former world champion and third seed Ratchanok Intanon of Thailand also kissed goodbye to her title hopes – losing a three-set thriller to China's He Bingjiao. The Youth Olympic champion won the 71 minute encounter 22-20, 14-21, 24-22.
Ratchanok was gunning her fourth title this year, having won the India Open, the Malaysia Open and the Singapore Open in a row.
Bingjiao will face another Japanese hopeful Aya Ohori who reached her first Superseries semi-finals with a hard fought 16-21, 21-17, 21-19 win in 79 minutes.
QUARTER-FINAL RESULTS
Women's Singles
Akane Yamaguchi (Jpn) beat Nozomi Okuhara (Jpn) 21-11, 23-21
Aya Ohori (Jpn) beat Ayumi Mine (Jpn) 16-21, 21-17, 21-19
Sun Yu (Chn) beat Sayaka Takahashi (Jpn) 21-14, 21-9
He Bingjiao (Chn) beat Ratchanok Intanon (Tha) 22-20, 14-21, 24-22
