MOST lovers of Chinese martial arts take the magical aspects of kung fu, as demonstrated by the flying fighters of legend and film, with a pinch of salt. But Wei Lei built his career in China on a claim that his mastery of tai chi, a branch of kung fu, had given him supernatural power. In a programme about kung fu that was broadcast on state television in 2015, Mr Wei demonstrated that he could keep a dove standing on his hand with an invisible force-field and smash the inside of a watermelon without damaging its rind. The broadcaster itself appeared to be among the credulous.

There were many sceptics, too. Earlier this year one of them stepped forward to challenge Mr Wei: Xu Xiaodong, a practitioner of mixed martial arts—a fighting form drawing on Eastern and Western traditions that began to take off in America in the 1990s (and is picking up fans in China). Mr Xu mocked tai chi as a slow-motion form of aerobics. Last month the two men decided to settle their argument in hand-to-hand combat. The fight on April 27th was quick and decisive. Just 12 seconds in, Mr Wei ended up on the ground, his nose bleeding.

A video of the clash spread rapidly online. Some commentators in China sided with Mr Xu, and urged him to expose other kung fu “masters”. Mr Xu promised to do so. His aim, he said, was not to disparage Chinese martial arts, but to expose deceitful practitioners.

But many netizens accused Mr Xu of trying to besmirch the country’s ancient fighting techniques: how, they asked, could a single fight prove anything? Guancha.cn, a news portal, said Mr Xu’s posts over the years on Weibo, a microblog website, had insulted the Chinese army and Mao Zedong. Ye Yincong of Lingnan University in Hong Kong wrote that the reaction demonstrated a common tendency in China to view the world in terms of a struggle between Chinese tradition and Western influence.

Some kung-fu fighters have expressed willingness to take up Mr Xu’s challenge. But faced with a barrage of hate messages, Mr Xu appears to have lost his zeal. On May 4th he appeared in a live video-stream, looking stressed. “I have lost my career and everything,” he said, implying the pressure had been affecting his work as a mixed-martial-arts coach.

The authorities appear eager to put an end to the debate. China’s president Xi Jinping is a fan of traditional Chinese culture, and says he wants to use it promote the country’s “soft power” abroad. The recent criticism of kung fu may have triggered too much questioning of it for his taste. On May 7th Mr Xu’s Weibo account was deleted, as was some of the online reporting and commentary about his fight with Mr Wei. Mr Xu told the BBC that he would keep quiet from now on, and study traditional Chinese martial arts.