Kazan: Neither has yet turned 21, yet Missy Franklin and Katie Ledecky are the `veterans` spearheading the USA`s quest for world championship gold medals when the swimming section starts on Sunday.
Between them, the pair won 10 golds as teenagers at the Barcelona world championships two years ago and they come to Kazan leading the USA`s medal charge a year away from the Rio de Janeiro Olympic Games.
With superstar Michael Phelps absent in Kazan after last year`s drink-driving conviction, the golden girls are set to shine for America.
"They`re two of the best athletes the world has ever seen," said the USA women`s head coach Dave Salo.
"They are our really young `veterans`. Katie only graduated from high school a few weeks ago."
Having left Barcelona with six gold medals two years ago, Franklin, 20, will be swimming in the 100 and 200m freestyle, plus the backstroke over the same two distances, and is sure to feature in the relays.
Ledecky, still only 18, has set herself a punishing schedule of racing in the 200, 400, 800 and 1500m freestyle, plus the relays.
Both are set to be in action on Sunday with Ledecky racing in the 400m freestyle heats before the pair could help the USA team in the 4x100m freestyle relay.Ledecky set world records over the 800m and 1500m freestyle in Barcelona, then bettered both last year.
She also set a new record in the 400m at the Pan-Pacific Games last August, but refuses to put herself under pressure in Kazan by predicting a medal haul.
"I don`t like to set time targets or goals, if I win and that`s a world record, then great," she said.
"I am just looking forward to getting up and racing, but I don`t think it`s good to get caught up in the records."
But Salo promptly turned up the heat by predicting the teenager will send more freestyle world records tumbling.
"We`re convinced Katie will do her best times here... and they just happen to be world records," he said with a grin.
As the US trials were held last year, Franklin comes into Kazan as an unknown quantity after failing to win any of her five events at her only pre-worlds warm-up meet in Santa Clara in June.
But the owner of a perpetually sunny disposition, Franklin takes it in her stride with her trademark smile.
"I was thrilled with Barcelona, that went almost perfectly," she said.
"I`m trying not think about that, I`m not swimming to get a medal here or a record, I`m just swimming to be the best I can be."
A back injury at last August`s Pan-Pacific Games tested Franklin`s mental strength, but she still finished with a gold, two silvers and a bronze.
"I got a lot of motivation from that. It was the first big road bump of my career," she said.
"I had an unbelievable amount of help. Our staff helped me out a lot, I wouldn`t have been able to walk if it wasn`t for them."Franklin has clear memories of the 200m freestyle final in Barcelona, which she won having pushed all the way by world record-holder Federica Pellegrini of Italy.
It promises to be a battle royal when the Kazan heats start in that event on Tuesday with both Americans and the Italian involved.
"It was one of my favourite races of the whole 2013 meet, I remember just taking it out hard, because I knew she was going to bring it back hard at the end," reminisced Franklin.
"The whole of the last 25 metres I just saw her coming back at me, I was thinking `oh my god`, it was the most painful thing ever."
There was a reminder of how young the pair are when a journalist shouted "got your driving licence yet, Katie?", which made the triple world champion blush.
"I`m still working on it," she replied.