It was the Canadian's first win over Okuhara in four years, including five straight defeats, and was Li's second top-tier semi-final, continuing her good recent form at the Japan Open.

Li lost the first game 21-23, but hit back 21-16 in the second game.

The decider was a thriller, with Li eventually pulling clear to seal the win 21-19 in a match that lasted more than 70 minutes.

Li will now play He Bingjiao, who defeated China's second seed Chen Yufei in a thriller, 15-21, 21-18, 21-18.

In the other half of the draw, Ratchanok Intanon exacted the perfect revenge for her defeat to Sayaka Takahashi at the China Open last week.

Intanon came through without dropping a game, 21-9, 23-21.  

She now faces Tai Tzu-ying, who battled to a 24-22, 22-20 victory over Gregoria Mariska Tunjung.

In the men's draw, Japan's top seed and back-to-back world champion Kento Momota continued his excellent form with a 21-15, 21-19 win over Malaysia’s Lee Zii Jia.

He faces a stiff semi-final test against Parupalli Kashyap, who played exceptionally well to dominate Jan Østergaard Jørgensen of Denmark, 24-22, 21-8.

Another semi-finalist looking strong is Chinese Taipei's Wang Tzu-wei.

He comfortably defeated the fifth seed, Anders Antonsen, in round two, and took care of fourth seed Jonatan Christie, 21-10, 15-21, 21-13 in the quarter-finals.

However, he will have his work cut out against second seed Chou Tien-chen, who was relatively untroubled against Indonesia's Shesar Hiren Rhustavito.

The semi-finals of the World Tour Super 500 tournament are tomorrow.