Yu was regarded as one of the brightest prospects in the sport when he won the Japan Open in 2014 followed by the world junior title in the same year.

He has failed to set the world alight since then but today, aged 20, caused the shock of the first round at the Geelong Arena.

The Chinese player won 11-7, 11-7, 6-11, 13-11, 15-17, 6-11, 11-3 to finally show what he is capable of once more.

"I think I came into the match fully prepared, especially with the tactics," said Yu. 

"Ovtcharov is not very familiar with my playing style. 

"I have watched him play for many years, so I know him well. 

"My mind-set changed a bit when victory was around the corner. 

"So in the deciding game, I tried to play more firmly. 

"This victory is a re-assurance. 

"After losing the sixth game, my coach just told me to believe in myself, there is still hope, at that time he did not need to emphasise the tactics. 

"He just told me to play firmly."

It was a bad day for highly ranked men's players with the third and fourth seeds also exiting the World Tour competition.

Third ranked South Korean Lee Sang-su lost in straight games to his countryman Jung Young-sik, 12-10, 11-3, 11-8, 11-8.

Japan's fourth seed Koki Niwa was beaten by China's unranked Zhou Yu, 11-7, 11-9, 8-11, 5-11, 11-5, 11-9.

Second seed Xu Xin of China opens his account tomorrow.

In the women's event, all of the top nine seeds remain in.

Number one ranked Kasumi Ishikawa of Japan beat compatriot Minami Ando 11-5, 7-11, 11-2, 9-11, 11-7, 11-4.

Second seed and Olympic team gold medallist Liu Shiwen of China beat Japan's Marina Matsuzawa in straight games, 11-8, 11-8, 11-9, 11-9.

Ding Ning, China's reigning Olympic and world champion, is also through.

The number seven seed beat Chinese Taipei's Cheng Hsien-tzu 11-7, 11-6, 11-6, 11-8.