SHANGHAI: China have won 28 of 32 gold medals awarded at the Olympics, but their supremacy could face its biggest test yet in Tokyo this summer.

Few countries have dominated a sport quite like China has in table tennis -- winning every gold for the last three Games -- but one state media outlet has broken ranks to warn of a "crisis".

Home advantage for fierce rivals Japan, inconsistent form among China's top players and uncertainty caused by the coronavirus pandemic suggest the world's most populous country might not have it all their own way when the delayed Tokyo 2020 Olympics start in just over two months.

Alarm bells rang earlier this month when what was billed as an Olympic simulation among China's players threw up some shock results.

Zhou Qihao, ranked 122nd in the world, stunned reigning Olympic singles champion Ma Long and world number one Fan Zhendong to win the men's title.

There was also an upset in the mixed doubles, which will make its Olympic debut in Tokyo.

State-run China News Service was unusually fierce in its appraisal, calling it "a wake-up call" and a "not-so-small crisis".

"The form of the main players is so up and down, can it be readjusted before the Olympics?" asked the news agency, warning about the threat from the Japanese team.

Mima Ito, the women's world number two from Japan, has been identified by Chinese media as the prime threat to another clean sweep in Tokyo.

There is also Japan's 17-year-old prodigy Tomokazu Harimoto -- whose parents are Chinese -- in the men's singles.Peng You, editor-in-chief of the online magazine Ping Pong, dismissed talk of a crisis.

Other pundits framed the surprising recent results as healthy competition, and proof of China's remarkable depth of talent.

"If problems are exposed at Tokyo instead of at this simulation, that would be the worst thing," said Chinese Table Tennis Association president Liu Guoliang.