IRVINE (UNITED STATES) - Katie Ledecky blazed to the third-fastest time in history Saturday in the women's 400m freestyle heats at the US Swimming Championships.
Katie Ledecky prepares to swim in the women's 400 meter freestyle prelims during the 2014 Phillips 66 National Championships at the Woollett Aquatic Center on August 9, 2014 in Irvine, California
The 17-year-old clocked 3min 59.89sec and said she thought she'd have plenty in the tank on Saturday night for a run at Italian Federica Pellegrini's world record of 3:59.15 -- set in the era of now-banned bodysuits.
"I'm looking forward to getting after it tonight," said Ledecky, who has already won gold this week in the 800m and 200m free.
Pellegrini's record and Ledecky's own 3:59.82, set in winning the world title at Barcelona last year, are the only faster times ever posted in the event.
And Ledecky is now the only woman to break four minutes in the event twice.
She said she didn't go out with record-breaking intent, but just carried over the confidence from a strong warm-up.
"I always like to get after it," Ledecky said. "I felt really good in warm-up and thought,'why not?'
"Hopefully, I’ll be better tonight."
Ledecky, who lowered her own world records in the 800m and 1500m free in June, was pleased with her "energy management" in swimming a controled first 100m.
"I think she did a real good job on the front half," her coach, Bruce Gemmell, said. "We'll see tonight if she can put a back half together with that."
In other heats, 18-time Olympic gold medallist Michael Phelps delivered a solid swim in a less familiar event, posting the fourth-fastest time in the 100m backstroke qualifying topped by Matt Grevers.
Grevers said he was "pleasantly surprised" to ease to a time of 53.11sec. Phelps said he needed to take it out faster in the final after qualifying in 53.76.
The 100m back didn't figure in Phelps's epic Olympic campaigns, but he's decided to take a stab at it in his return from a near two-year retirement.
Missy Franklin led the way into the final of the women's 100m backstroke, where she'll seek to add another title to her 100m free and 200m backstroke wins.
Micah Lawrence and Kevin Cordes, winners of the women's and men's 200m breaststroke titles on Thursday, topped the times in the 100m breaststroke preliminaries.
Matt McLean, winner of the men's 200m free led the way into the men's 400m free final.