(Reuters) - Katie Ledecky surprised a few people when she blew away the field to win the 800 metres freestyle at the 2012 London Games, becoming at the age of 15 the youngest winner of the longest event on the women's Olympic schedule.
But that performance was just the start for the American, who is now the world's dominant female middle and long distance freestyle swimmer.
Ledecky has set seven world records in the past two years and holds all of the marks for the 400, 800, and 1500 metres freestyle.
While none of those records have come in 2015, she has still set the fastest times in all three distances, by margins of 10 seconds or more in the 800 and 1500, and should peak nicely for the world championships in Kazan.
"I'm feeling really good at this point. I couldn't be more excited," Ledecky told reporters recently after spending three weeks of altitude training in Colorado, before heading to Croatia for the American team's training camp.
"As long as I'm feeling really good in practice and confident about my swims I should be in a good shape going into worlds."
Ledecky will look to defend her world titles from 2013 in the 400, 800 and 1500, but will also have a crack at the 200, a distance at which she does not necessarily expect to win, but thinks she can challenge for a medal.
That confidence, no doubt has come from the 'black line fever' she has developed in her brutal training regime.
She has nine training sessions a week in the pool, with each generally notching between 5500 and 8000 metres.
She also does two 'dry land' sessions, which focus on strength training, flexibility and injury prevention.
The world championships in Russia are midway through a two-year plan that Ledecky and coach Bruce Gemmell mapped out at the start of 2014 as they looked to the Rio Olympics, though the 18-year-old Ledecky was firmly focussed on her immediate future.
"I'm just focusing on Kazan. I'm definitely not looking past Kazan right now," she said.
"In terms of where I am now compared to last year, it's hard to compare," she added of her superb 2014 season when she broke five world records in the space of two months.
"We've found something I can work on to improve. I'm very motivated."
(Reporting by Andrew Both in Cary, North Carolina; Editing by Greg Stutchbury)