Low blows

However, Zhang was facing another ugly opponent spawned by fears of the virus－prejudice.

Her opponent, Joanna Jedrzejczyk, a five-time defending champion in the 52-kilogram (115-pound) division, stirred controversy by posting a mock promotional poster on social media that depicted the Polish fighter standing behind Zhang and wearing a gas mask.

The image was accompanied by laughter emojis.

In public, Zhang kept her cool, but the stress was starting to take its toll.

She said she cried to her mother when they spoke by phone, but eventually found the courage to carry on.

"During that period, normal training was challenged by the travel, the time differences, new food, having no coach (at times), and biased views from social media posters," she said.

"After travel through several countries I was, in fact, rather tired."

Before the fight Zhang said she was "really irritated" by Jedrzejczyk "making jokes about the outbreak and our country".

In the ring she let her fighting skills do the talking, defeating the Pole in a split decision in front of a roaring crowd at T-Mobile Arena in Las Vegas.

"All fighters deserve respect from one another in the octagon. I don't like people hitting each other with trash talk," Zhang said after her stirring victory.

Two months after her gutsy win, a more thoughtful Zhang said she had learned a greater lesson from her victory, which was tied up with the global fight against the virus.

"I insisted on advocating joint efforts in the fight against COVID-19," she said.

"Unity for a shared future is the strongest immunity."

Home, at last

But sharing the joy of the successful defense of her title with family and friends was put on hold due to the pandemic.

Zhang spent more than 40 days in the US recovering from the bout and, with reduced airline schedules, trying to get a flight back to China.

She arrived in Tianjin on April 20, and after completing her 14-day quarantine at a hotel there, left for Beijing on May 5 to resume training.

During her quarantine in Tianjin she trained in her room using equipment provided by the sports bureau of Hexi district.

She killed time reading books on philosophy and studying English. Zhang said she appreciates the work of the late left-wing British philosopher Bertrand Russell, a renowned mathematician and logician known for his freethinking and having courage in his convictions.

While in quarantine, Zhang said she read one of his books and watched a documentary about him online. "In essence, the Chinese martial arts are a kind of philosophy," she said.

Zhang was born in 1989 into a working class family in Handan, Hebei province. She developed a passion for martial arts as a child, and joined a school to hone her fighting skills.

Because of an injury, she abandoned training at the age of 17 and worked as a cashier and kindergarten teacher in Beijing.

In 2014, she returned to competitive martial arts and became a professional athlete.

Zhang secured her place on the country's martial arts honor roll when she defeated Brazil's Jessica Andrade in August to become China's first, and so far only, UFC champion.