The Australian swimming star Mack Horton has signalled that his feud with China's Sun Yang is as bitter as ever, refusing to share a podium with Sun after the 400m final at the world championships.
Horton finished second as Sun claimed a record fourth-consecutive 400-metres freestyle final in South Korea but when the time came to stand on the dais for the medal presentation, Horton stood behind it.
The Australian also refused to pose for photos with his rival, who was suspended for doping in 2014, but happily posed with Italian bronze medallist Gabriele Detti.
Asked what his overriding emotion was, Horton replied: "Frustration. I think you know in what respect."
"I don't think I need to say anything.
"His actions and how it has been handled speaks louder than anything I could say."
Sun is currently facing allegations of doping rule violations that could result in a ban from the 2020 Tokyo Olympics and he has requested a public trial at the Court of Arbitration for Sport in September to defend himself.
The World Anti-Doping Agency is challenging a decision by FINA, swimming's world governing body, merely to warn him over incidents during a doping control team's attempts to take blood and urine samples at his home in China last September, while allowing him to continue competing.
Sun said "I am aware of the rumours that have been going around, but I try to just concentrate on my swimming and I will keep trying to put a lot of effort in my swimming."
The Chinese world champion said he was aware Horton has a problem with him.
"Disrespecting me was OK, but disrespecting China was unfortunate," Sun said.
"I feel sorry about that."
Sun's presence at the world meet has drawn the ire of some swimmers, including Horton, who is the only swimmer to beat Sun in the past eight years, taking gold in the 400m freestyle at the 2016 Rio Olympics.
After that race, Horton called Sun a "drug cheat" for his three-month doping suspension in 2014.
Horton's refusal to take the podium caught the eye of some of his former and current teammates.
"Absolutely awesome to see Mack Horton protesting clean sport by not getting up on the podium next to Sun Yang #cleansport," tweeted David McKeon, who swam the 4x200m relay with Horton in Rio.
Five-time Olympic gold medallist Melanie Wright wrote: "Congratulations Mack Horton - Olympic and now World champion; shame you won't get the gold medal for it #cleansport."