The rise of American swimming star Caeleb Dressel has made Australia's Kyle Chalmers dramatically re-think his Olympic 100m freestyle title defence.
Chalmers, 18, admitted he would have to broaden his program with a bigger focus on the 200m freestyle if he were to have the endurance to compete with the breakout star of the world swimming championships at Budapest.
Chalmers looked on in awe from the stands at Duna Arena as Dressel cut a swathe through his rivals, racking up six gold medals, including a dominant 100m freestyle victory.
The 20-year-old American is expected to notch a record seventh gold as part of the men's 4x100m medley relay on the final night.
Chalmers missed the world titles in order to have corrective heart surgery but admitted he could waste no more time preparing his Olympic defence after witnessing Dressel's heroics.
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"I have realised I have to start picking up my game, training hard," said Chalmers, who will return to racing on the European World Cup circuit next month.
"I will really have to start focusing on that 200m as well so I can compete with him.
"Because Caeleb is racing 50m, 100m, 200m free, 50m and 100m fly plus relays.
"I can't just focus on one event."
Dressel has made plenty of statements at Budapest but the one that made Chalmers take notice was his scorching 47.17 second 100m freestyle winning time.
It was the fastest time to win a 100m title since the supersuit era ended in 2009.
And Dressel was more than half a second faster than Chalmers' winning time in Rio.
Chalmers said the 200m freestyle would be his next focus as he tries to come up with a strategy to stop Dressel at Tokyo 2020.
He already has big plans for Australia's 4x200m freestyle relay team at the 2018 Gold Coast Commonwealth Games.
"It would be amazing to win the 4x200m on home soil next year (Gold Coast) and I think we are a good shot at that."
Chalmers also couldn't contain his excitement over Australia's 4x100m relay prospects.
Dual world champion James Magnussen (shoulder) is expected back next year along with Chalmers, adding to Australia's current sprint stocks of Cameron McEvoy and young gun Jack Cartwright.
As a result, Chalmers reckoned he was no guarantee of clinching a Commonwealth Games 4x100m relay berth.
