Beijing: Chinese sports fans and local media have turned on Australia's newest Olympic swimming sensation Mack Horton, accusing the 20-year-old of "taunting" home favourite Sun Yang by calling him a "drug cheat" to his face in a post-race press conference.

Horton had already raised the stakes in the electrifying rivalry between the two swimmers before their 400-metre freestyle final, saying he had "no time or respect for drug cheats", referring to Sun's three-month doping ban in 2014. He then backed up his talk with a nerveless swim to hold off a fast-finishing Sun, clinching Australia's first gold at the Rio Olympics.

Controversy: Sun Yang and Mack Horton. Credit:Getty Images

Footage of a devastated Sun bursting into tears while attempting to give an interview in the media mixed zone immediately after the race went swiftly viral on Chinese social media.

The top-trending hashtag "Sun Yang Don't Cry" amassed more than 47 million views on China's Twitter-like Weibo within hours.