The pair became involved in a heated exchange as they left the pool area, with a fuming Sun pointing at Scott's chest and telling the Glaswegian "You loser, I'm winning, yes!" as they walked down the stairs.

The race was already dramatic enough. Sun was awarded gold by default after Lithuanian Danas Rapsys, who touched the wall first, was disqualified for moving on the blocks.

Scott, who dead-heated for bronze, stood on the dais for the anthems but stepped aside when they concluded and refused to shake hands or be photographed with Sun. The non-Chinese crowd roared their approval before Sun kicked things off verbally, shouting and gesticulating wildly at Scott.

A volatile Sun continued the verbal altercation as they left the pool but Scott kept his calm, smiled and continued walking.

"I'm team Mack," said Scott, who was called a "loser" by Sun as the pair left the pool following the medal ceremony.

"If [Sun] can't respect our sport then why should I respect him? I think a lot of people, everyone in swimming, got behind what Mack did."

The International Swimming Federation, FINA, said it would send a "warning letter" to Scott and Sun over the incident.

"The FINA Executive met today in Gwangju (KOR) to analyse the situation [that] occurred during the men's 200m free victory ceremony and has decided to send a warning letter to athletes Duncan Scott (GBR) and Sun Yang (CHN)," FINA said. "Both competitors had... inadequate behaviour on this occasion, which is not acceptable in accordance with the FINA Constitution Rule C 12.1.3."

Sun Yang gets in bronze medalist Duncan Scott's face after the 200m freestyle medal ceremony (Sun won gold after Lithuanian Danas Rapsys was DQed for a false start). Scott and Sun did not appear to shake hands, and Sun shouted in Scott's direction earlier in the ceremony. pic.twitter.com/0ilhiSorqt

- Nick Zaccardi (@nzaccardi) July 23, 2019

The protest was a clear show of solidarity for Horton's move on the first night of the championships, when he refused to share a podium with arch-rival Sun. He called Sun a "drug cheat" at the Rio Games, while Sun enters these titles under fresh scrutiny after a vial of his blood was smashed with a hammer before it could be tested.

He was cleared by a FINA doping panel but WADA has appealed the matter to the Court of Arbitration for Sport in September.

A host of swimmers in Gwangju had spoken up in support of Horton but Scott was the first to put actions behind words.

British teammate Adam Peaty, who has lashed FINA already for their handling of the Sun matter, said he would have done the same thing.

"[Scott] is completely right," Peaty said. "If people are booing [Sun], it's for a reason. He should be asking himself now - should I really be in this sport when people are booing me? If I was swimming I wouldn't even get on the podium for that matter".

"I think the most important thing as a sports person is that you have a right to a voice and Duncan showed his voice tonight and so did the crowd."

Sun was scheduled to hold a press conference but did not arrive after being taken to doping control for a regulation test.

The drama overshadowed a pulsating race, with both Sun and Rapsys chasing hard over the first 100 metres as Australia's Clyde Lewis made it a genuine acid test going into the back half of the race.

Lewis could not sustain the pace, sliding back to finish seventh in a time of 1:45.78 as Rapsys and Sun surged towards the wall. Rapsys was the man, bursting clear to stop the clock at 1:44.69, with Sun second in 1:44.93s.

But his joy at winning the world title lasted just seconds. The big screen was quick to flash up the dreaded DQ next to his name.

After taking out the 400m freestyle on night one, Sun would be getting another gold medal, much to the joy of his travelling pack of fans that drape signs with his name all over the arena.

Rapsys was shattered by the result but it didn't stop Sun celebrating enthusiastically once more.

Everyone enjoys a showman in sport but on this occasion, given the nature of his victory, the timing was not ideal. His antics would not have endeared him to many of his fellow swimmers, many of whom are already unabashed critics.

You can be sure of one thing about Sun; wherever and whenever he swims, there is drama and controversy. He found himself in the middle of Horton's podium protest on night one and now collects yet another major meet gold medal on the back of a minute movement from Rapsys, who sped through the mixed zone without stopping to speak to media.

"Yeah it was a bit bizarre, poor bloke, I'm sure he's shattered but shit happens," Lewis said.

SMH/The Age