Elena Rybakina has clinched the last spot for next month's WTA Finals by beating Victoria Mboko to reach the Pan Pacific Open semi-finals.
The 2022 Wimbledon champion, who has won two WTA 500 titles this year, beat 19-year-old Mboko 6-3 7-6 (7-4) to seal her place in the end-of-season event.
The WTA Finals, which features the top eight singles players and doubles teams of the year, starts on 1 November in Saudi Arabia.
Kazakhstan's Rybakina needed to reach at least the semi-finals in Tokyo to pass Russian 18-year-old Mirra Andreeva in the race for the eighth and final spot.