Keri-Anne Payne likes a challenge. For one she has her wedding to organise next month in Aberdeen. An autumn wedding in the north of Scotland – she will marry fellow Olympic swimmer David Carry – is an event able to defy even the best prepared; being an open-water swimmer might be just what is required.
Payne is the best women's open-water swimmer in the world and will dive into the Serpentine at lunch-time as favourite to win gold, but it is an event that is on a par with Scottish weather for its sheer unpredictability. There will be 25 swimmers in the field, including all the top-10 finishers from last year's world championship in Shanghai.
Payne was first over the line in Shanghai, to claim her second world title, but the entire top 10 finished within 20 seconds of each other – that after 10km. Compare that to the men's 1500m freestyle in the pool, where 20 seconds only covered half the eight-strong field finishing, and it offers an indication of the competitiveness of the women's event.
"I don't think Michael Phelps ever thought Ryan Lochte would ever beat him, but he has," said Payne. "That's the beauty of the Olympics – it's all about who is the best swimmer on that day."
It has been a long wait for Payne to get into the water. She had her final practice swim in the Serpentine – which has been praised by the competitors for the cleanliness of its water – yesterday under the guidance of Mark Perry, Britain's open-water coach. "She's in good form and she's ready to go," said Perry.
It is a race she has been preparing for since last July when she won the world title. It has been an exhaustive process, 10 two-hour sessions a week and one of five hours for a race that will leave her aching from head to toe – most swimmers finish with thumping headaches after two hours in the water.
"I am always pushing my body to the brink of potential illness because you have to push it as far as we can so it breaks down and rebuilds itself better," said Payne. "That's how the training works, so you are always at risk of pushing it too far. We're conscious swimming outdoors for too long could push you over the edge. You learn that as you get more experienced – when to take time out and how far to push it."
Four years ago she competed in the pool as well, but this time she has had to watch as her team-mates have struggled, with the honourable exception of Michael Jamieson and Rebecca Adlington, who will be a bridesmaid at Payne's wedding, and look on as elsewhere Britain's medal favourites have, largely, matched expectation.
She shared a room with Adlington in Shanghai, doing sudoku to pass the time, but this time it has been a more challenging wait. Britain failed to win a gold in 32 events in the pool – a silver and two bronze means the swimmers will fall short of their medal target of five to seven but a gold from Payne would offer a welcome dose of painkilling.
Four years ago Payne won a silver medal behind Larisa Ilchenko. The Russian is not in London this time and the main challenge will come from the likes of Martina Grimaldi a Neapolitan policewomen who took silver in Shanghai, the Australian psychology student Melissa Gorman, and Marianna Lymperta of Greece, the world bronze medallist. But any of the top 10 is capable of having a decisive day, or a disastrous one.