By Alan Baldwin

RIO DE JANEIRO (Reuters) - Katie Ledecky put another golden, and late, night behind her on Thursday and focused on winning a fourth title at the Rio Games in her favorite 800 meters freestyle event.

The 19-year-old did not push too hard in the heats after anchoring the U.S. to victory in the 4x200m freestyle relay late on Wednesday, but still set an Olympic record time of eight minutes 12.86 seconds.

Her closest rival, Hungary's Boglarka Kapas, was nearly seven seconds slower in 8:19.43 with Britain's Jazz Carlin third in 8:19.67.

"(Coach) Bruce (Gemmell) just told me to think about my rhythm the first 200 and then he didn't give any other instructions," said the world record holder and defending champion who has become unbeatable at the distance.

"Well, he told me not to take a hard stroke so I tried not to."

Ledecky said she had got to bed at about 3.15 a.m and, not being one for sleeping in, was up again at about 9 a.m.

"I'm happy. I get tonight off, tomorrow morning off and get to race again," she said

Ledecky has already won the 200m and 400m freestyle and is going for the individual golden triple. She also has the 4x200 relay gold and a 4x100 silver.

Spain's 2012 silver medalist Mireia Belmonte, who won the 200m butterfly on Wednesday, also had a quick turnaround and was back in action in an earlier 800m heat, securing the last slot for the final in 8:25.55.

That left New Zealand's 2015 world championships silver medalist Lauren Boyle out in the cold after she finished ninth.

Before the women's longest distance, the men began their shortest with Ukraine's Andrii Govorov fastest in the 50m freestyle heats.

U.S. team mates Nathan Adrian and Anthony Ervin were second and third.

In the women's 200m backstroke, Hungary's Katinka Hosszu remained on course for her fourth individual gold of the Games after leading the way in two minutes 06.09 seconds, ahead of Canada's Hillary Caldwell.

Maya DiRado of the United States was third fastest as she also chases her fourth medal in Rio.

U.S. team mate and Olympic champion Missy Franklin, who won a relay gold on Wednesday despite not being selected for the final, made the cut with the 11th fastest time.

"We do a lot of work for my backstroke at training camps, tuning little things here and there, and I felt like I was able to translate a lot of that into my race," Franklin, the four times gold medalist from 2012, told reporters.

(Reporting by Alan Baldwin, editing by Toby Davis)