Zhang earned singles and team titles at the London 2012 Olympics and followed that with team gold and singles silver at Rio 2016.

He also secured singles gold medals at the 2011 and 2013 World Championships and is considered among the greatest players in the history of the sport.

But, despite remaining among the most recognisable athletes in China, the 30-year-old has struggled in recent years and barely competed internationally since a shock second-round exit to South Korea's eventual bronze medallist Lee Sang-su at last year's World Championships in Düsseldorf.

He has slumped to 168th in the world rankings and began his qualifying campaign with an 11-8, 11-6, 11-9, 11-4 win over Italy's Niagol Stoyanov at the Queen Elizabeth Stadium.

The 30-year-old today beat fellow Chinese Ma Te, a defensive player who beat Chinese Taipei's 2008 world junior champion and current world number 33 Chen Chien An yesterday, in six tough games 11-9, 12-10, 9-11, 5-11, 16-18, 5-11.

Hong Kong's world number seven Wong Chun Ting is the top seed and progresses automatically into the main draw.

South Korea's Lee is the second-seed while German trio Patrick Franziska, Bastian Steger and Ruwen Filus are among other seeds as they seek to build on their silver medal at this month's team World Championships in Halmstad.

Kasumi Ishikawa of Japan starts as top seed in the corresponding women's singles draw.

Feng Tianwei of Singapore is seeded second while Wang Manyu leads the Chinese contingent.

World number 11 Doo Hoi Kem is the leading home player.

Action is due to continue until Sunday (May 27).