Australian Olympic swimmer Mack Horton has sparked controversy at the opening night of the World Championships in South Korea after refusing to share the podium with a Chinese rival.
Sun Yung, who faces allegations of doping, claimed his fourth-consecutive 400m world title at the event in Gwangju, while Horton came in second.
The Australian refused to stand next to Sun, who has previously served a three-month doping suspension, on the podium, later telling reporters he was "frustrated".
"I think you know in what respect," he added.
The Australian also refused to shake hands with Sun after the race.
"I don't think I need to say anything," he said.
"His actions and how it has been handled speaks louder than anything I could say."

China's Sun Yang, centre, holds up his gold medal as silver medalist Australia's Mack Horton, left, stands away from the podium. Source: AP
'Disrespecting China'
While the move has been praised by the Aussie's teammates, it's created a global furore.
Sun criticised the move as 'disrespecting China'.
“I was aware that the Australian athlete had dissatisfaction and personal feelings towards me,” he said.
“But it was unfortunate because disrespecting me is okay but disrespecting China was very unfortunate and I felt sorry about that."
Horton is already disliked in China, after he labelled Sun a "drug cheat" at the 2016 Olympics in Rio de Janeiro, following the Chinese swimmer's three-month suspension.
Last year, Sun, a 10-time world champion was accused of destroying vials of his blood that were due to be taken for testing.
However, he was not punished by world swimming governing body FINA because the drug testers did not show adequate identification.
The World Anti Doping Agency has appealed the finding, which could see Sun banned from the 2020 Olympics in Tokyo.

Mack Horton was happy to pose Italy's Gabriele Detti, who won bronze. Source: AP
Sports world divided
The Australian swimmer's actions have divided the sporting world, with former Australian Sports Anti Doping Authority CEO Richard Ings saying Horton should be served a "hefty penalty".
"I am no fan of Sun Yang," he tweeted.
"But he has served his suspension for a doping violation and he has been cleared by a FINA panel of refusing to provide a sample. Innocent unless and until proven guilty.
“Not standing on the podium with him should attract a hefty penalty.”
But others have praised the move, including Australian swimmer David McKeon, who competed in the the 4x200m relay with Horton at the 2016 Olympics in Olympics in Rio de Janeiro.