Rio Olympics 2016: Katie Ledecky breaks Olympic record as Carlin sets personal best
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|Hosts: Rio de Janeiro Dates: 5-21 August Rio time: BST -4|
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American swimmer Katie Ledecky set a new Olympic record in the heats of the women's 400m freestyle - as Britain's Jazz Carlin qualified second fastest.
Ledecky won her heat in three minutes 58.71 seconds, just outside her world record time of 3:58.37.
Carlin's time of 4:02.83 was a personal best, as she reached the final, which takes place at 03:01 BST on Monday.
GB's Georgia Davies, James Guy, Chloe Tutton and Chris Walker-Hebborn progressed in their respective events.
Ledecky, who is bidding for the women's 200m, 400m and 800m freestyle titles in Rio, beat the previous Olympic record by almost three seconds.
"That one felt pretty easy," said the 19-year-old. "That's the easiest it's felt going under four minutes."
The US swimmer could become the first to complete the 200m, 400m and 800m treble since compatriot Debbie Meyer at the 1968 Mexico City Games.
On Saturday, Ledecky anchored the US women's 4x100m relay team to a silver medal at Rio's Olympic Aquatic Centre.
Britons make progress
Carlin was the only British swimmer competing for a place in an Olympic final in the morning session, but a number of Britons reached the semi-finals of their events on Sunday.
James Guy - who was sixth in the 400m freestyle final on Saturday - comfortably advanced to the semi-finals of the 200m freestyle (02:11 BST, Monday).
Guy finished second in his heat, but team-mate Cameron Kurle was 35th overall and missed out.
Georgia Davies was third in her heat of the 100m backstroke to advance to the evening's semi-finals (03:36 BST) as the seventh-fastest qualifier, while Chloe Tutton was 12th fastest in reaching the semi-finals of the 100m breaststroke (02:29 BST).
In the same event, Molly Renshaw was second in her heat but only 23rd overall.
Chris Walker-Hebborn reached the semi-finals of the 100m backstroke (03:12 BST) as the 10th-fastest qualifier.
Elsewhere at the Olympic Aquatics Centre
Russia's Yulia Efimova, cleared to compete at the last moment after a positive meldonium test in March, was booed by sections of the Rio crowd as she won her 100m breaststroke heat in 1:05.79.
Efimova was second-fastest behind the 1:05.78 of American Lilly King, and ahead of 19-year-old London 2012 gold medallist Ruta Meilutyte of Lithuania, who trains in Plymouth.
Elsewhere, Katinka Hosszu, who set a new 400m individual medley world record on Saturday, returned to book her spot in the 100m backstroke semi-finals with the equal fourth-fastest time.
In the men's backstroke, France's Camille Lacourt topped qualifying in 52.96sec, with the top four swimmers all touching within a tenth of a second. China's Xu Jiayu was second quickest ahead of Australia's world champion Mitch Larkin.