KAZAN, Russia (AP) Katie Ledecky touched the wall, turned around, spit out some water, curled her mouth into a big smile and began waving her finger.
For a swimmer who is getting accustomed to breaking world records, this one was a bit of a surprise.
The American teenager improved her own mark in the 1,500-meter freestyle at the world championships Monday in morning heats.
The 18-year-old Ledecky completed the marathon-like race in 15 minutes, 27.71 seconds - shaving 0.65 seconds off the mark she set at last year's Pan Pacific championships in Australia.
''I'm in quite a bit of shock right now,'' Ledecky said. ''I was barely even focusing on this morning's swim. I was so relaxed. ... I realized kind of toward the end because I could see people waving.''
It's the fourth time Ledecky has broken the record in the 1,500 and she'll have a chance to improve it again in Tuesday's final.
Ledecky also holds world marks in the 400 and 800 free. She was just off her record pace in winning the 400 free Sunday.
''It's probably one of the coolest world records I've broken,'' Ledecky said. ''Each one is really unique, but just sort of how relaxed and calm I was it's pretty neat and hopefully I can carry that energy through the rest of the week.''
While the Kazan Arena was only half full, Ledecky's American teammates and family members in the stands were going wild, and she acknowledged them after climbing out of the temporary pool.
''I knew where my parents and brother and uncle were sitting and I could see them waving as well,'' Ledecky said.
It was the second world record of the meet after Sarah Sjoestrom of Sweden broke one in the 100 fly semifinals Sunday.
Jessica Ashwood, the second-placed swimmer in Ledecky's heat, finished more than a lap behind. Others were more than two laps behind. That gave Ledecky plenty of time to savor the moment, while resting on the lane ropes.
Lotte Friis of Denmark qualified second in 15:54.23.
The 1,500 - the longest event in the pool - is not an Olympic race for women.
Ledecky's biggest challenge of the meet could come Tuesday when she'll race against teammate Missy Franklin and a loaded field in the 200 free semifinals after the 1,500 final.
''The 200 is going to be a big race,'' Ledecky said. ''I should have 20 minutes in between and that should be plenty of time.''
Franklin, meanwhile, is learning how to deal with the lingering effects of her back injury. She should be glad she won't have to deal with Katinka Hosszu, otherwise known as the ''Iron Lady,'' for the remainder of the 100 backstroke.
While it was only good for fifth, the 20-year-old Franklin swam her fastest time of the year Monday.
Hungary's Hosszu led the event in 58.78 seconds ahead of Australians Emily Seebohm and Madison Wilson, while Franklin touched in 59.59.
Hosszu then announced she was scratching the rest of the event to focus on the 200 individual medley final later Monday. She qualified first in that event, too, and is planning to swim five more individual events this week.
Franklin was injured at last year's Pan Pacific Championships in Australia and she still undergoes physical therapy two or three times a week to strengthen her back.
''It's my first 59 of the season. It felt great. It's a tough field,'' Franklin said. ''After last summer I have this new appreciation of getting up there and not worrying about injury.''
Aiming for his second gold of the championships, China's Sun Yang topped the 200 free heats in 1:46.00. James Guy, the British swimmer who took silver behind Sun in the 400 free Sunday, was again second, just 0.10 behind.
World-record holder Paul Biedermann of Germany qualified third and Australia's Cameron McEvoy was fourth. American standout Ryan Lochte only barely advanced to the semifinals in 13th.
''I'm glad that's over. That felt horrible,'' Lochte said, describing his swim as ''a tactical disaster.''
Always the favorite in the 400, 800 and 1,500 free, Sun's best result in the 200 was silver at the London Games.
China's anti-doping agency revealed in November that Sun served a three-month ban earlier that year after testing positive for the banned stimulant trimetazidine. After his 400 win, Sun lashed out at the criticism stemming from his ban, saying it showed ''a lack of respect.''
In the men's 100 back, Mitchell Larkin of Australia qualified first in 52.50 with Olympic gold medalist and defending champion Matt Grevers of the United States second in 53.21.
Fresh off her doping ban, Yuliya Efimova of Russia got the crowd inside the Kazan Arena going by leading the 100 breaststroke heats in 1:06.31.
Andrew Dampf can be followed at www.twitter.com/asdampf