China's table tennis stars usually demolish their rivals but they may be fighting a losing battle after mounting a rare challenge against more formidable opposition — their own sports system.

In a rare show of dissent, Ma Long, Fan Zhendong and Xu Xin — the world's top three men's players — downed paddles at last month's China Open in Chengdu, saying they were too heartbroken to play after the removal of head coach Liu Guoliang.

It is highly unusual for Chinese athletes to publicly break ranks with the state sports system, and follows apparent attempts to censor online comment, according to a website which monitors social media in China.

China's athletes are often groomed from childhood in an intense training environment, bringing success particularly in medal-heavy Olympic sports like badminton, diving and gymnastics — and especially table tennis, where China has won all but four gold medals since it joined the Games programme in 1988.

After failing to appear for their second-round singles matches at the China Open, the "Chengdu Three" posted messages on social media saying they were too saddened by Liu's axing to play on.

They quickly apologised, along with Liu — but the all- conquering men's team was then pulled from this week's Australian Open because of "tiredness". Nothing more has been heard since.

The row has its roots in the suspension of women's head coach Kong Linghui, the former Olympic champion known as the "Ping Pong Prince" who is being sued over a gambling debt to a Singapore casino, according to reports.

After an internal investigation found "several deep- seated problems in the (team's) management", Liu was removed as overall head coach and named as a vice-president of the Chinese Table Tennis Association, the body said.

The problems affecting Chinese table tennis come after a shake-up in badminton, where Li Yongbo quit after 24 years as head coach in April, following a prolonged slump in form.

But public revolts are rare, mainly because of the strength of China's sports system and the culture of putting the country before the individual, experts say.

"It's so institutionalised and it's 'country-first' and all about China and not the individual," said Mark Dreyer, founder of China Sports Insider, which analyses the country's sports business.

"At the Olympic level people have been criticised for thanking their parents before they thank their country," he said, adding that Chinese officials often want to "piggy-back" on an outstanding sportsman's success.

"Individualism, putting yourself above the country and the team is frowned upon, so when people become big stars and start getting individual endorsements for example — rather than team endorsements — that causes a lot of problems with the old style of thinking."

While open rebellion by sports stars is seldom seen, one of the best known cases also came in table tennis — He Zhili, who later became the Japanese national champion Chire Koyama.

She was a star in China but did the unthinkable and defected to arch-rival Japan, claiming that she had resisted an order to lose a 1987 world title clash to a Chinese team- mate.

Swimmer Sun Yang fell out with authorities over his relationship with an air hostess, and he was also banned after his involvement in a car accident while driving without a licence.

Ning Zetao, another of China's top swimmers, was kicked off the national team in February for signing sponsorship deals without official consent.

Badminton great Lin Dan risked the wrath of his handlers by dating team-mate Xie Xingfang — now his wife — despite such relationships being forbidden.

The biggest name to break free of the system is Li Na, who won Asia's first two Grand Slam tennis singles titles before she retired in 2014.

The outspoken Li hit success late in her career after she made the tough decision to go it alone with her own coaching set-up and organising her own sponsorship.

"It still staggers me, given how successful she was, why they have not allowed it more and why they persist with the fear of losing control and earnings," said Dreyer.

Given China's success in table tennis, top players are household names and the "Chengdu Three" have sparked much debate and speculation, trending on social media for several days.

"Only China's sports administration can beat the Chinese table tennis team," quipped one user on China's Twitter-style Weibo, in a comment that was later deleted.

Reflecting the level of interest, the state-aligned Global Times newspaper published a lengthy analysis of the table tennis row.

"While the recent protest exposed discontent with the nationalised sports system, there is no denying that in ping pong at least, that system has an undeniable record of success," said the article, praising it as "a well-oiled machine".

But it also conceded there was "unprecedented outcry and anger towards the nationalised sports system that places collectivism first".