Rebecca Adlington aims to lift Team GB's aquatics despair

Defending champion fastest in qualifying as rest of British women fail to deliver medals

It is now or never. As has become the pattern for British swimming, it falls to Rebecca Adlington to deliver on the nation's final genuine hope of a gold medal in home waters. Tonight Adlington will swim the final of the 800 metres freestyle, 16 lengths of the London Aquatics Centre pool, at the end of which lies a historic prize – if she can take it.

No British woman has won three Olympic gold medals, nor has any British swimmer retained an Olympic title – and how British swimming needs Adlington to make history tonight, in particular the women's team. This is the strongest line-up of female swimmers Britain has ever assembled at a Games but their return has not matched expectations. Adlington is the only one to have earned a medal, a gutsy bronze in the 400m freestyle, while a number of her team-mates have appeared overawed by the occasion.

When she is ushered into the call room ahead of tonight's race Adlington will herself be a bundle of nerves. Despite all she has achieved, she always is. Ahead of the British Olympic trials here in March her psychologist resorted to telling her to "man up" as she was gnawed by nerves – that in a woman who already has two Olympic titles to her name. But once in the water everything changes, and that has been the difference between Adlington and her team-mates: she rarely fails to deliver when it most matters. At the trials she swam the fastest time in the world this year.

Yesterday morning she made a statement and qualified fastest for the final, 0.11sec ahead of Lotte Friis, her great Danish rival. Last year at the World Championships in Shanghai the two women matched each other stroke for stroke before Adlington edged clear in the last few metres to claim a first world title, her victory coming by less than a second in a swim that lasted 8min 17sec.

In Beijing in 2008 the Briton's relentlessness broke Friis, who took bronze, and now they are set for a third head-to-head. The American Katie Ledecky is a threat to both, however. She recorded the second fastest time in the world this year to reach the Olympics but, while these Games have shown that 15-year-old swimmers can win gold medals, it would be some achievement. Kate Ziegler is one threat Adlington will not have to worry about. The American, ranked three and a former double world champion, caught flu in London and failed to qualify.

"I'm pleased with that," said Adlington of her swim. "I put my head down and went for it, especially after the 400m heat where I just scraped in. It will be a battle but hopefully we'll see what I can do."

Adlington will swim from lane four from where she can control the race – her outside lane in the 400m free denied her any chance of challenging for gold – and there is every reason to suppose she will. Her training has gone according to the plan carefully constructed by her coach, Bill Furniss. There is a confidence surrounding Team Adlington, although it will not be evident in that call room.

Friis too has confessed to nerves. In 2009 she earned her first major title by beating Adlington in the 800m final of the World Championships in Rome. That came during the Briton's post-Beijing slump – she did not even make the final when Friis won the European title a year later. But the refreshed Adlington was back in Shanghai and does not appear to have gone away.

There will be another British woman in action tonight after Lizzie Simmonds put a shaky heat swim behind her to qualify for the final of the 200m backstroke. Simmonds, the European champion, finished fifth in her semi-final to reach a second Olympic final. However, it will need a personal best if the 21-year-old is to challenge the likes of Elizabeth Beisel and Missy Franklin for a podium place. Stephanie Proud missed out on a final place by less than a third of a second.

In last night's concluding final, Fran Halsall was 0.22sec short of a bronze medal in the 100m freestyle. Halsall was in contention throughout but faded at the last to finish sixth. The gold went to the Dutchwoman Ranomi Kromowidjojo. Halsall still has the 50m free to come, but the longer distance was rated as her better chance of a medal.