Sunday, 30 July 2017: Australia's Mitch Larkin says he is more determined than ever to bounce back after experiencing a worst case scenario at the world swimming tiles in Budapest.

When dual defending champion Mitch Larkin arrived at the world swimming championships at Budapest, he mapped out every scenario.

And the former FINA Male Swimmer of the Year admitted his results at the eight-day meet at Duna Arena would be filed under "worst case".

But Larkin said he was more determined than ever to make his shock switch to new coach Simon Cusack work despite admitting he would "have a bit of a cry" upon his return to Australia.

Larkin's woeful meet only got worse when he couldn't qualify for the 50m backstroke semi-finals on day seven of the world titles at Duna Arena.

The defending 100m-200m backstroke champion in Hungary was a shadow of the man who dominated the 2015 world titles.

He not only didn't qualify for the 200m final at Budapest, he finished second-last in the semis.

And the 24-year-old stumbled in his other title defence, finishing sixth in the 100m final.

"I planned for all options this week," Larkin said.

"I prepared for worse case scenario which is probably this.

"It's hard. I haven't tried to think about it too much. It is still quite raw."

Two years ago, Larkin was on top of the world.

He became the first man in 10 years to complete the 100m-200m world titles double at Kazan, Russia instantly making him the man to beat at Rio.

It ensured he became the first Australian - and backstroker for that matter - to earn Male Swimmer of the Year honours.

Yet Larkin made the shock call to dump long time mentor Michael Bohl and link with the world beating Campbell sisters' coach Cusack ahead of the 2016 Olympics.

Alarm bells are still sounding after his ill fated world titles defence in Hungary.

But Larkin said he was more focused than ever to make his coaching switch work, even if his dual world titles defence ended in tears at Budapest - literally.

"It is not probably until I get home when I will look back at the week, have a bit of a cry, chat with Simon and go from there," Larkin said of his results.

Larkin admitted it was always going to be tough to reclaim his 2015 world titles form under Cusack, saying his new mentor told him it would take 18 months for them to click.