Rebecca Adlington claimed her second bronze medal of the London Olympics as 15-year-old Katie Ledecky produced the second fastest 800 metres freestyle in history to take gold for the United States.

Ledecky led from start to finish as the expected duel between Britain's Adlington and Denmark's Lotte Friis failed to materialise.

Instead, Ledecky went straight out and moved further ahead from the halfway stage, under world-record pace all the way until the final metres to touch in eight minutes and 14.63 seconds, with only Adlington ever having gone faster in Beijing. With 200 metres left, Spaniard Mireia Belmonte Garcia attacked to overhaul Adlington and finish second in 8mins 18.76secs.

Adlington picked up her second third place of the week, following her 400m bronze, touching in 8:20.32.

"It was such a difficult race, she swam so fast," Adlington told BBC1. "She swam absolutely incredible. I think she's only really young as well - 15 - it's amazing.

"The 800 was my event. I think the pressure and everything, the expectation, everything going into this meet has been a little bit of a battle but I'm so pleased with that. I would have liked the time to have been a bit quicker, I'm not going to lie. I've done that time all year and I don't know what happened. Everything just kind of caught up with me.

"I gave it my absolute all and I'm sorry that I didn't get the gold for everyone that was expecting me to. But I am so proud and pleased to get a bronze medal - it's nothing ever to be embarrassed about. I hate it when people say that silver or bronze is losing because you have not done my sport.

"Swimming is one of the hardest sports to medal at. We're not like other sports. It is so, so difficult and I hope the public realise this this week and hopefully will be proud of me for getting that bronze."

Ledecky announced herself on the world stage at the United States trials in June when she won in a time bettered this year only by Adlington. The teenager has had a startling 12 months in the water. This time last year her best was around 8:36 before she started cutting her times dramatically.

She was impressive in Thursday's heats although it was Adlington who had qualified fastest, a whisker ahead of Friis, the Dane admitting she had come "to spoil the party".