Setbacks at world championships have underlined China's decline in international badminton, with the lack of formidable leaders casting a shadow on the nation's prospects for the 2020 Tokyo Olympics.

Once considered a showcase of Chinese talent, the BWF World Championships have become a major stumbling block. At the 2018 edition, which wrapped up in Nanjing on the weekend, the host claimed just two gold medals - in men's doubles and mixed doubles - equaling its worst outcome in two decades at the marquee tournament.

The celebration of Japan's Kento Momota after winning the high-profile men's singles final against Chinese young gun Shi Yuqi on Sunday evening silenced fans more accustomed to watching homegrown athletes dominate the podium.

Meanwhile, none of China's female players made it to the singles final, which saw Spain's Carolina Marin beat PV Sindhu of India. The women's doubles final was a showdown between Japanese pairs. It marked China's first world title loss in the discipline since 1995.

Perhaps more disconcerting is the fact no one has emerged as a legitimate successor to Lin "Super" Dan, who spearheaded China's supremacy for 10 years after winning men's singles gold at the 2008 Beijing Olympics. He is still pursuing a record fifth Games appearance in Tokyo.

"I am still in contention, but a shift of power in the sport has been happening. We will for sure face tougher challenges at each major event down the line," said the 34-year-old Lin, who lost to Shi in the third round in Nanjing.

Stunning Lin and reigning Olympic champion Chen Long on his way to the final, Shi raised hopes on the ascent of a new star, but the aggressive style of Momota, Japan's first men's singles world champion, exposed the immaturity and lack of mental fortitude in Shi's game.

"I don't think I am anyone's successor at the moment," the 22-year-old Shi said after losing to Momota 21-11, 21-13. "I am still young and I need to improve every aspect of my game. Brothers Long and Dan are still role models that I look up to."

With Lin in the twilight of his career and Shi too young to take the reins, it's supposed to be Chen, 29, carrying Team China through challenges posed by younger and hungrier opponents, such as Momota, 2017 men's single world champion Viktor Axelsen of Denmark and promising Indian player Kidambi Srikanth.

However, the lack of consistency in Chen's game underlined by his singles losses at the past three Thomas Cup finals, the biennial world men's team championships, has raised questions on his mental strength as a team leader even though he defeated Malaysian former world No 1 Lee Chong Wei to win the singles title at the 2016 Rio Olympics.

Lin, a five-time world singles champion and the only repeat Olympic gold medalist, stressed that the slow progress of his younger compatriots compared to the rise of young challengers in Asia and Europe is a factor.

"No big progress simply means regression. This is the crucial nature of competitive sports," he said.

From January to July, Japanese and Indonesian players each won 11 titles across disciplines on the BWF World Tour while China managed to collect only four, according to a Xinhua report.

After China bagged just two badminton golds at the Rio Games and the men's squad's was dumped from the 2017 Thomas Cup at home, national program head coach Li Yongbo was forced to step down in April last year, triggering a series of personnel changes in key coaching positions.

A bullish boss in the top position for 24 years, Li's winner-takes-all mindset and outspoken personality drew some criticism, but the team's winning momentum under his tutelage - highlighted by 18 Olympic gold medals from 1996 to 2016 and 10 Sudirman Cup world mixed team championship titles - silenced doubters.

The dismissal of women's team coach Zhang Ning following the squad's semifinal loss to host Thailand at the 2018 Uber Cup in May was considered an aftershock of Li's departure.