The unseeded Indian pair won 21-17, 21-14 in 42 minutes against the 13th-ranked Japanese combination, who captured the Canada Open title this year and finished runners-up at the Denmark Open Super 750 last month.

Treesa and Gayatri advance to the round of 16 where they will face third seeds Rin Iwanaga and Kie Nakanishi of Japan, the world number five pair. The head-to-head record stands at 1-1, with the Indians winning their most recent meeting 21-16, 21-12 at the BWF World Championships in New Delhi earlier this year.

In men's doubles, Hariharan Amsakarunan and MR Arjun progressed to the pre-quarterfinals after third seeds Aaron Chia and Soh Wooi Yik of Malaysia retired hurt while trailing 11-6 in the opening game.

Dhruv Kapila and Radhika Sharma exited the mixed doubles qualifiers following a 21-16, 21-15 defeat to the United States pair Chen Zhi Yi and Francesca Corbett.

India's men's doubles pair Satwiksairaj Rankireddy and Chirag Shetty, along with women's singles player Malvika Bansod, withdrew from the tournament after initially being listed to compete.

Lakshya Sen, who climbed eight places to 10th in the race to the BWF World Tour Finals after winning the Hylo Open earlier this month, begins his singles campaign on Wednesday. The Commonwealth Games champion aims to break into the top eight, the qualification cutoff for the season-ending Finals in China from December 9 to 13.

At last year's Kumamoto Masters, Lakshya reached the semifinals before losing to home favourite Kenta Nishimoto in three games. He also finished runner-up at the All England Open this year.

Satwiksairaj and Chirag, ranked 12th in the men's doubles world rankings, have won two BWF Super 750 titles this season — the Singapore Open in May and the China Masters in September — and were runners-up at the Thailand Open. A strong showing in Japan could boost their World Tour Finals qualification hopes.

Two-time Olympic medallist PV Sindhu has already secured her place in the BWF World Tour Finals after consistent performances on the World Tour circuit. She returned to a career-high world number six ranking in women's singles following her Hylo Open title victory over Denmark's Line Kjaersfeldt 21-12, 21-14 on Sunday.

The Hylo Open triumph marked Sindhu's second BWF World Tour title of the season after her Japan Open win in July. She also reached the French Open final, losing to world number one An Se Young, and made the semifinals at the Malaysia Open and Australian Open. Sindhu won the World Tour Finals title in 2018.

The tournament continues on Wednesday with Lakshya Sen's opening match and the round of 16 clashes including Treesa and Gayatri against Iwanaga and Nakanishi.