TOKYO (AFP) - China's Sun Yang, the 'enfant terrible' of competitive swimming, is set to undergo another test of his fragile temperament at the world championships after a turbulent 2016 Rio Olympics.
Likewise, all eyes will be on Singapore's Joseph Schooling in Budapest this month after he stunned Michael Phelps to win Singapore's first-ever Olympic gold last year.
Bad boy Sun spearheads China's assault and will be looking to exact revenge after Australian Mack Horton robbed the hulking Chinese star of his Olympic 400 metres freestyle in Brazil.
Emotions boiled over after a pulsating final in Brazil when Horton branded Sun a "drug cheat" - a reference to a three-month doping ban his rival served for taking a banned stimulant Sun said was for a heart complaint.
The pair traded insults, triggering a diplomatic row with Chinese state-run media calling Australia a "second-class citizen" of the West, before Sun bounced back to win gold in the 200m.
Expect sparks to fly again in Budapest with Sun and Horton set to lock horns in the 200m and 400m, as well as the 800m and 1,500m freestyle - events Sun has dominated in recent years.
"As captain of Chinese Swimming team, I need to shoulder more responsibility," the multiple Olympic and world champion told Xinhua news agency.
"I must encourage my team-mates, help them steady their mood and lead them to make breakthroughs in the world championships."
A notable absentee for China will be pin-up Ning Zetao, who will not be in the Hungarian capital to defend his 100m freestyle world crown, citing an abdominal injury after failing to qualify.
Xu Jiayu will compete, however, after taking Olympic silver in the 100m backstroke behind American Ryan Murphy.
Schooling's shock Rio victory over Olympic legend Phelps - who dead-heated for silver with Chad le Clos and Laszlo Cseh - in the 100m butterfly final puts him firmly in the firing line in Budapest.
But the 22-year-old clocked 50.96 seconds in Austin, Texas earlier this month, just 0.09 off American Caeleb Dressel's world-leading time, to suggest he could be peaking at just the right time again.
"Caeleb has the fastest time this year but I am not going to let anyone take that number one spot from me," Schooling told reporters.
With Phelps ending his storied career in Rio, Japan's Kosuke Hagino has been tipped to take over as the world's premier medley swimmer.
The 22-year-old won gold in the 400m medley in Rio but was comfortably beaten by the great American in the 200m final.
Whether or he can convert Olympic gold and silver into double gold in Budapest could depend on countryman Daiya Seto, who has had Hagino's number in recent domestic competitions.
Seto, who took bronze in Rio over 400m, is chasing a hat-trick of world titles in the longer medley after capturing gold in Barcelona and Kazan.
Japanese schoolgirl Rikako Ikee, a five-event national champion, will be another name to watch in the freestyle and butterfly.