The 28-year-old Indian will take on another Japanese, World No. 3 Nozomi Okuhara in the quarter-finals on Friday.
India's badminton ace Saina Nehwal defeated World No. 2 Akane Yamaguchi of Japan for the first time in four years to enter the quarter-finals of the Denmark Open, in Odense, on Thursday.
Later in the day, more good news was in store of India as Sameer Verma held his nerve to beat Asian Games champion Jonathan Christie to reach the men's singles quarterfinals.
Saina, an Olympic bronze-medallist who has dropped to World No. 27, registered an easy 21-15, 21-17 win over second-seeded Yamaguchi in the pre-quarterfinal match that lasted just 36 minutes.
The 28-year-old Indian will take on another Japanese, World No. 3 Nozomi Okuhara in the quarter-finals on Friday.
This was Saina's second career win over Yamaguchi, who has won six times in the head-to-head encounters between the two.
Saina's first win against Yamaguchi came in 2014 during the China Open.
Since then, Yamaguchi has enjoyed upper hand against the Indian. The earlier two meetings this year -- Uber Cup in May and Malaysia Open in June -- also went in the Japanese's favour.
Saina trailed 0-4 initially in the opening game, before she made a fine comeback to level the scores at 10-10. But from there, Nehwal showed tremendous resolve and reeled off five straight points to take a 15-10 lead and then widened i to 19-12.
Yamaguchi recovered a bit but Saina grabbed five game points at 20-15 and then easily pocketed the first game.
In the second game, it was Saina's turn to take the lead initially as she raceed to 7-2 but Yamaguchi caught her up at 11-11.
After that, it was a close tussle between the two as they were locked 17-17.
At that stage, Saina cinched four points on the trot to win the second game and clinch the match.
It was a good day for India in the women's doubles as well with Ashwini Ponnappa and N Sikki Reddy upsetting seventh seeds from South Korea, Lee Ho See and Shin Seung Chan, 18-21, 22-20, 21-18 to enter the quarter-finals.
