By Clara Ferreira-Marques

LONDON (Reuters) - World champion and home favorite Rebecca Adlington may have missed out on the top spot in her first race this week, but she set herself up for gold on Thursday, becoming the fastest qualifier for her preferred event, the grueling 800 meters.

Adlington became a household name in Britain after she ended the country's long drought in swimming by winning two gold medals in Beijing four years ago. Her feat, but also her refreshing, down-to-earth manner, won the then-teenager huge support in a country hungry for Olympic success.

If she wins gold in Friday's final, the 23-year-old would be the first Briton to successfully defend an Olympic swimming title.

"I just put my head down and went for it, especially after the 400 heat, only scraping in," Adlington said in reference to her qualifying for the 400 final in eighth place, though she did manage to win bronze from the outside lane.

"I was like, 'I am not risking that, even if I give it a little bit more than I should do, I'd rather get in safely', so I just went for it and I am pleased with that time," she said.

"Obviously it's going to be a battle tomorrow but I've just got to see what I can get."

Adlington is the world record holder and has swum the fastest 800 meters this year, but she will face challenges from 15-year-old U.S. swimming prodigy Katie Ledecky and her long-time rival, Denmark's Lotte Friis.

"She's the home crowd favorite, she's the world champion and the Olympic champion - she's the one to beat for all of us," Friis said.

"She had a shaky start in Shanghai too and still won. I am not underestimating her."

Adlington came second in the 400 in the Shanghai world championships last year but took gold in the 800 in one of the races of the championships as she and Friis went stroke for stroke until the Briton surged clear on the final length.

HOME TOWN

Adlington is from Mansfield in central England, a town with a population of less than half her Twitter following.

On her return from Beijing, she was given a parade around Mansfield on an open-top bus, greeted by 15,000 well-wishers and presented with a pair of Jimmy Choo shoes - in gold. The municipal pool and a local pub were renamed in her honor.

But life after the Olympics was not easy.

She won bronze in the 400 free and 4x200 relay at the Rome world championships in 2009 after refusing to wear a polyurethane bodysuit, which are now banned.

"I hadn't done the hard yards and I got found out in Rome. I learned so much more out of losing in 2009 than winning in 2008," she said later.

Her face, and her ever-ready smile, are familiar to millions of Britons, making her one of the country's best-known Olympians and a public face of the London Games.

She has said the attention is not always easy, but has worn the pressure of a nation's expectations lightly, firmly focused in the pool but happy, out of it, to chat amiably with Twitter followers and teammates, to publish a picture of her messy room in the Olympic Village, and to discuss her love of shoes.

"People who are in sport realize you can't win everything," she said in one newspaper interview before the Games.

"It's nice that I have the support but I won't be thinking 'oh, Joe Bloggs is going to slag me off if I don't swim well'."

After the Games, she plans to join fellow British swimmers Joanne Jackson and Ross Davenport on a 450km cycle across Zambia in four days for a children's AIDS charity.

(Editing by Greg Stutchbury)