SINGAPORE - Deliver another clean sweep or salaries could be docked and demotions could be enforced.

China's table tennis coaches have been warned ahead of next year's Tokyo Olympics, where they are expected to win all the gold medals on offer - a feat achieved in the last three Olympics.

But, with the rise of Japan in recent years, China's dominance could come to an end in Tokyo, said South Korean Olympic gold medallist Ryu Seung-min, who prevented China from winning a third straight men's singles gold in 2004 when he defeated Wang Hao in the final in Athens, Greece.

"The 2020 Games may be historic because there are really dangerous young players such as (Japan's) Tomokazu Harimoto and the Chinese players are a bit nervous because these players are growing so fast… so that's why we can expect some other countries to win the gold medal," said Ryu, 36, at the inaugural Step South-east Asia Youth Sport Leaders Camp at Temasek Polytechnic on Saturday (March 9).

Since table tennis was introduced as a medal sport at the 1988 Seoul Olympics, China have won all but four gold medals.

Ryu, who was part of the South Korean team that won the bronze and silver medals at the 2008 and 2012 Olympics respectively, has "no doubt" the Chinese will triumph in the women's singles as well as men and women's team events.

But, with the men and women's doubles having been dropped before Beijing 2008 in favour of the team events, the new mixed doubles is a good opportunity for other countries to strike gold, he added.

The men's singles will be the most keenly contested with world No. 4 Harimoto seen as China's biggest threat after he became the youngest player to win the International Table Tennis Federation (ITTF) World Tour Grand Finals last December at 15 years and 172 days.

Ryu believes Harimoto, who will turn 16 in June, could deliver Japan's first gold medal in the men's singles if he continues to improve and harness the home support to his advantage in his maiden Olympics next year.

Citing his experience at his first Olympics in 2000, the former world No. 2 said: "In 2000, I expected to win a medal and I prepared really hard but I failed because there was so much pressure on me participating in the Olympics for the first time.

"We have tournaments all around the world, but the Olympics are just different. There was huge pressure in my mind because I kept thinking, 'This is the real Olympics'.

"Some Chinese players (such as Zhang Jike and Xu Xin) have experience and participated in Olympics before, but this is Harimoto's first time.

"He's young and the Olympics are held in his country so there is very big pressure on him but, if he overcomes this kind of obstacle, then he can be an Olympic champion."

Earlier, Ryu shared with 138 participants from 17 Asian countries how difficult it was to train 10 hours a day.

But, whenever he felt like giving up, he relied on five words to keep going - courage, knowledge, challenge, engage and language - as well as confiding in his family and friends to overcome difficulties he faced in his career.

"It was boring and tough on me physically and mentally… but athletes must be patient when you're achieving your goals. Sometimes things get hard for you, but you can overcome these obstacles," he said.

Speaking to the media after the talk, he said: "I enjoyed talking to them because I saw that they're really passionate. Those five key words were most important for me and I hope this kind of motivation will be helpful for them when they have some tough situations."