Xu, the second seed, defied the trend of the highest-ranked players suffering early exits as he beat Jin Ueda of Japan 7-11, 11-8, 11-3, 7-11, 11-8, 11-1 at the Geelong Arena.

The 28-year-old, a member of the Chinese squad which won the team gold medal at the 2016 Olympic Games in Rio de Janeiro, will play Germany's Patrick Franziska in the last eight.

Franziska, the 14th seed, fought back from two games down to edge India's Sharath Kamal Achanta 12-14, 9-11, 11-9, 11-3, 7-11, 11-7, 11-8.

The only other seeded player still left in the men's singles draw is Japan's Tomokazu Harimoto, who overcame compatriot Yuki Hirano 11-8, 11-3, 6-11, 11-5, 11-4.

Fifth seed Harimoto will face China's Zhou Yu, an 11-3, 14-12, 12-10, 11-5 winner over India's Sathiyan Gnanasekaran, in the quarter-finals.

Today's results means a qualifier is guaranteed a place in the final as there are no top seeded players remaining in the top half of the draw.

In the women's singles event, sixth seed Feng Tianwei crashed out after she suffered an 11-7, 11-6, 11-7, 13-11 defeat at the hands of Chinese qualifier He Zhuojia.

Fourth seed Miu Hirano of Japan is safely through following a 11-4, 11-8, 11-2, 9-11, 16-14 victory against Feng's team-mate Yu Mengyu.

Japan's Mima Ito joined Miu in the next round after she defeated Zeng Jian, also of Singapore, 11-9, 11-5, 7-11, 9-11, 11-2, 2-11, 11-7.

The tournament in the Australian city continues tomorrow.