Sun Yang speaks to media at the final of the men's 800-meter freestyle event during the swimming competition at the 2019 World Championships in Gwangju, South Korea on Wednesday. Sun finished sixth in the final. Photo: VCG

Chinese swimming star Sun Yang has been given the cold shoulder on the podiums twice during the world championships, but Tuesday's goading "You're a loser, I'm a winner" at British swimmer Duncan Scott seemed unseemly behavior for a champion.

Following the incident, Sun was given a warning by FINA - swimming's world governing body - for "inadequate behavior" during the men's 200-­meter freestyle victory ceremony.

The scene followed Sunday's 400-meter freestyle ceremony when Australian Mack Horton refused to join Sun for a podium photo. 

American swimmer Lilly King said that plenty of swimmers at the athletes' village applauded Horton's protest. 

As a multiple champion, Sun, now 27, can outswim his opponents in the pool, but the battle outside to defend his reputation will arguably be harder. 

He arrived at the worlds ­after FINA cleared him of anti-doping rule violation, as collectors failed to provide the proper validation papers. People close to Sun smashed a vial of blood with a hammer to prevent anti-doping testers leaving with a sample in a September 2018 test.

That suspicious move was the major source of protests against him. 

It's easy to see why Team Horton is protesting against Sun - not China as Sun claims. 

Chinese backstroke specialist Xu Jiayu did not receive the same treatment from Australian Mitch Larkin when they were both on the podium after the 100-meter backstroke. 

Athletes win by continually honing their skill and hard work, but Horton could have chosen a different place to make his point against Sun rather than on the podium.

Horton's teammate Thomas Fraser-Holmes, also a freestyle specialist, served a 12-month suspension starting in 2017 for missing three drugs tests in 12 months. But outspoken Horton did not say a thing to his teammate. 

If Horton is trying to keep sport clean by requesting a ban on Sun, why did he not speak a word about his teammate for dodging doping tests? 

Richard Ings, former chief of Australian Sports Anti-­Doping Authority who claimed he was "no fan" of the Chinese champion, said Sun should be considered "innocent unless and until proven guilty."

Following the incident, some fans of Sun also went too far by flooding Horton's social media account with vitriol including death threats. 

Some Chinese argued that Western swimmers have a biased view against elite Chinese athletes and never has a swimmer been boycotted for his or her medal-winning performance. 

Take Japanese butterfly swimmer Rikako Ikee as an example. She won six gold medals in a single Asian Games at 18 last year but leukemia interrupted her regular training since February, making her unable to compete. 

She received a warm moment on Monday, when women's 100-meter fly medalists - all likely to be her major rivals if Ikee competes again - sent a message of support through their palms. 

Now Sun is under a cloud by the Court of Arbitration for Sport's (CAS) September hearing after the World Anti-Doping Agency has decided to appeal. Sun has requested a public hearing, according to his lawyers. A CAS ruling in favor of Sun's innocence would be the best way to defend the sport's cleanness and integrity.