Swimming: Campbell eyes worlds glory from Olympics heartbreak

BARCELONA, Catalonia - Australia's Cate Campbell has vowed to use her Olympic heartbreak as motivation at swimming's world championships, which start Sunday, having posted the fastest 50m freestyle time this year.

The 21-year-old clocked 24.27sec in Adelaide in April, faster than Holland's Olympic champion Ranomi Kromowidjojo, and is determined to bounce back after illness hit her hopes at the London Olympics.

Having helped Australia win Olympic relay gold in the 4x100m freestyle, Campbell was hit by gastroenteritis which ruled her out of the 100m freestyle.

Still suffering from the effects, she only made the semi-finals of the 50m freestyle in London, but is itching to prove herself in Barcelona.

"I was watching four years of work go down the toilet - literally," she said of her London experience.

"It was heartbreaking, but it motivated me.

"I always look for the silver lining and after three weeks off I was ready to get back in the pool.

"I knew the world hadn't seen what I was capable of in London.

"Maybe it was a positive thing, it really drove me to continue swimming at a high-level until Rio (2016 Olympics), so maybe it was the extra motivation I needed."

The tall Queenslander is no stranger to illness-related setbacks.

In 2010, she had to take a year off after suffering from glandular fever and post-viral fatigue, which left her immune system vulnerable as she slept more than 12 hours a day.

"It was incredibly difficult," she said of her 2010 illness, which came two years after she won 50m freestyle and 4x100m freestyle relay bronze as a 16-year-old at the 2008 Beijing Olympics.

"I had started out so young and it seemed like I had a big, bright future, but then illness struck.

"It was where friends and family became important.

"I had to really reasses how I viewed swimming - up until then it was my life, now it is a part of my life.

"I had amazing support systems around me. It gave me the time and patience to work on getting well.

"They say patience is a virtue, but by the time those two years were finished, I was very virtuous - I could have been a nun.

"I am just pleased to have had some good training behind me coming into Barcelona and I'm ready to go."

Despite clocking a faster 50m time than Kromowidjojo's 24.30sec in 2013, Campbell insists the Dutch star, who won the 50m and 100m freestyle gold medals in London, is the sprint favourite.

"She's a dual Olympic gold medallist. Come on, you don't become that without being a fantastic swimmer, she is the one to beat," said Campbell.