Chinese giant Sun Yang came into the Asian Games with the reputation as a one-man wrecking crew and left savouring his redemption -- and in tears at his own achievements.

The three-times Olympic champion barely broke sweat in scooping four individual gold medals from 200 metres freestyle up to the 1,500m in Jakarta, screamed on by an army of flag-waving cheergirls who had made the trip from China.

Sun sparked controversy at the last Asian Games in 2014 by sneering at the Japanese national anthem after being upset by Kosuke Hagino in the 200m.

Four years older and wiser at 26, swimming’s enfant terrible showed his softer side, bursting into tears after Friday’s 1,500m victory.

“I didn’t train or swim the distance at big competitions since 2014,” sobbed the Chinese superstar. “It means to much to me that all the hard work has paid off. It’s a huge boost for me.”

Sun launched a charm offensive in Indonesia, aware that a hostile crowd will do little for his hopes at the 2020 Tokyo Olympics.

“The Japanese swimmers are our rivals -- whether it’s Hagino or Daiya (Seto) I can learn a lot from them,” said Sun after winning the 1,500m title at a third successive Asian Games.

“Hagino is a cool guy, an inspiration to me. But I need to raise my level for the Tokyo Olympics -- whether it’s the 200m, 400m, 800m or even the 1,500m. I’ll have to work 200 percent or even 300 percent harder.”

“The battle with Japan doesn’t end here,” he added. “We’ll meet again next year (at the world championships) and in 2020.”

- China crisis -

China’s talismanic team leader brushed off talk of crisis after Japan pipped the favourites in overall medals after a titanic six-day struggle.

“We had a very young team,” he shrugged. “I tried to take on more events to try and be a role model.”

“I was shattered and thought about pulling out of the 1,500m,” added Sun.

“But I toughed it out to try to inspire.” Although never pushed in Jakarta, Sun did enough to show that he will be a threat in Tokyo after stepping up his long-distance training earlier this year.

“I’ve got my confidence back, especially in that 1,500m -- I’m buzzing now,” said Sun, who set the current world record of 14:31.02 in the 2012 London Olympic final.

But the path back from the darkness he felt in Rio two years ago has been a long and winding one for Sun.

He lost his Olympic 400m title, and Australian rival Mack Horton rubbed salt into the wounds by calling him a “drug cheat” over the three-month ban Sun served in 2014 for taking medicine prescribed for a heart condition.

Unfinished business fuels Sun’s drive for the Tokyo Olympics. “My back hurt but you have to battle through if you want you rewards,” he said. “It’s all about gritting your teeth and pushing through the pain.”