KAZAN, Russia (AP) -- Missy Franklin and Katie Ledecky are the workhorses of the U.S. team at the world swimming championships.
Four individual events in eight days for each of them and that's not including any relays, making them the busiest Americans in the water at Kazan Arena.
The women are back on the world stage for the first time in two years, each having built formidable legacies since the 2012 London Olympics. Franklin and Ledecky combined for 10 gold medals at the 2013 worlds in Barcelona. Franklin won a record six while Ledecky took home four, along with two world records.
They are the dominant U.S. swimmers with Michael Phelps missing the meet because of his suspension by USA Swimming for his second DUI arrest.
Franklin arrives in Russia as a 20-year-old professional, having competed for two years in college and now represented by a Hollywood agent. Ledecky is an 18-year-old high school graduate without a driver's license who is deferring college until after next year's Olympics.
Ledecky gets her program started with the 400-meter freestyle Sunday on the opening day of the meet. Franklin begins Monday with preliminaries in the 100 backstroke.
Franklin and Ledecky will have a rare showdown in the 200 free, with Franklin the defending champion. Ledecky, a distance specialist, is dipping into the sprint ranks where her endurance could prove useful in outlasting a stellar field expected to include two-time world champion Federica Pellegrini of Italy and Femke Heemskerk of the Netherlands.
"I have a blast every single time I race Katie. She makes me a better athlete," Franklin said Friday. "The whole field is going to be wanting that and giving their heart in that race."
Ledecky added, "I hope we can both get into the final."
Since leaving college last spring, Franklin moved back home to Colorado and resumed training with her childhood coach. She competed in just one meet before worlds, leaving her a bit uncertain about what she can accomplish in Kazan, where a temporary pool has been set up in the city's soccer stadium.
"This meet is such a good indicator of things that you need to work on especially for next year for Olympic trials, so I'm excited to race to see where I am and where my competitors are," she said.
Also on Franklin's program is the 100 free and 200 backstroke. She injured her back at last summer's Pan Pacific Championships in Australia, calling it the first "road bump" in her career. She still does physical therapy two or three times a week to strengthen her back.
"I truly believe it won't ever happen again," she said.
Ledecky set her first world records in the 800 and 1,500 freestyles two years ago, and she has since added the world mark in the 400 free.
"We are convinced Katie is going to do her best times here," U.S. women's coach Dave Salo said.
Ledecky brushed off talk of lowering her world records, saying, "I don't like to set specific time goals. I'm looking to improve. If the records come, great."
On the men's side, Tyler Clary, Connor Jaeger and Michael McBroom will swim three individual events. Ryan Lochte has a lighter than usual schedule, with just the 200 free and 200 individual medley, and any relays. He will try to add to his career haul of 23 medals from worlds.
"I never think about the medals I won because that's the past," he said. "I keep going forward."