Sun beat the fourth seed 11-8, 11-5, 11-7, 11-8 in the round of 32 before defeating ninth seed Lee Sangsu of South Korea 11-3, 8-11, 11-8, 11-8, 11-7 in the round of 16. 

Awaiting him in the last eight of the ITTF World Tour Platinum event at the Hokkaido Prefectural Sports Center is set to be fellow Chinese Liang Jingkun, who came from behind to overcome Japan's Jun Mizutani 3-11, 9-11, 11-8, 16-14, 12-10, 11-5 in the round of 16.

"I am happy to have won against him," Sun said after his victory over Harimoto.

"He is one of the top players in the world – I am really happy for the win. 

"I was mentally prepared for the match and played my best against him.

"Perhaps the pressure of playing at home got to him, but I realise I had more time and space than expected against him. 

"I am thankful for the trust my coaches put in me and hopefully I did not disappoint."

Among the other players through to the quarter-finals is top-seeded Chinese Fan Zhendong after he beat Japan's Kazuhiro Yoshimura 11-2, 11-7, 11-6, 13-11. 

Next up for him is set to be fifth-seeded compatriot Ma Long, who defeated South Korea's Jeoung Youngsik 11-9, 7-11, 11-9, 9-11, 9-11, 12-10, 11-5 in the round of 16.

There was a surprise loss for second seed Lin Gaoyuan of China as he fell to an 11-9, 11-9, 19-21, 9-11, 7-11, 9-11 defeat at the hands of Chinese Taipei's Lin Yun-Ju.

Lin's reward is a meeting with seventh-seeded Brazilian Hugo Calderano, a 5-11, 11-5, 9-11, 11-7, 9-11, 11-5, 11-3 winner at the expense of Germany's Ruwen Filus.

The one other quarter-final tie pits third seed Xu Xin of China against eighth seed Jang Woojin of South Korea.

Both had straight-games wins in the round of 16 with Xu overcoming Chinese Taipei's Chuang Chih-Yuan 11-6, 11-7, 17-15, 11-4 and Jang beating Germany's Dimitrij Ovtcharov 11-7, 11-8, 11-9, 11-7. 

In the women's singles event, Japan's Hitomi Sato defeated top seed Ding Ning of China 12-10, 6-11, 3-11, 12-10, 11-6, 11-9 to book her place in the quarter-finals.

She had earlier overcome Chinese Taipei's Chiu Ssu-Hua 11-7, 10-12, 11-6, 11-9, 11-6 in the round of 32.

Next up for Sato is fellow Japanese Miu Hirano, who beat compatriot Miyu Nagasaki 8-11, 11-5, 11-5, 12-10, 11-9 in the round of 16.

Nagasaki was unable to repeat her heroics from her opening match when she defeated fifth-seeded Chinese Zhu Yuling 11-6, 5-11, 11-9, 11-7, 11-9.

Second seed Chen Meng is through to the quarter-finals on the back of an 11-5, 11-4, 11-4, 14-12 victory over Hong Kong's Lee Ho Ching.

Standing between her and a semi-final berth is fellow Chinese Gu Yuting, who followed up a 7-11, 11-7, 11-8, 11-9, 12-14, 12-10 win over defending champion Mima Ito of Japan by overcoming countrywoman He Zhuojia 11-5, 7-11, 5-11, 11-5, 11-3, 11-9.

The other two quarter-finals are all-Chinese affairs with Liu Fei set to face fourth seed Liu Shiwen and Sun Yingsha going up against third seed Wang Manyu.

Liu Fei beat eighth seed Cheng I-Ching of Chinese Taipei 13-11, 8-11, 11-8, 11-5, 11-7 before defeating Japan's Sakura Mori 11-13, 9-11, 11-6, 11-6, 12-10, 7-11, 13-11.

Sun also eliminated a seeded player today, overcoming sixth-ranked Kasumi Ishikawa of Japan 11-8, 11-6, 11-5, 11-6 in the round of 16.

Action in Sapporo is due to continue tomorrow.