In the latest part of our weekly #olympicthursday series profiling leading British hopes, BBC chief sports writer Tom Fordyce looks at the Olympic chances of marathon world record holder Paula Radcliffe.
Eight years ago in Athens she was hot favourite for gold. Four years ago in Beijing she was considered a decent shot. Now, heading into her fifth Games, what chance does Paula Radcliffe have of finally winning an elusive Olympic medal?
Radcliffe is arguably the greatest distance runner Britain has produced.
She has won World Championships, destroyed British records at every distance from 3,000m up and, with her marathon best of two hours 15 minutes and 25 seconds, she holds a record that could go unchallenged for decades to come.
Now aged 38, a mother of two, she is again hunting the one major honour missing from her CV. The trouble is, again the problems are mounting.
"I don't think she will win the Olympics," was the straightforward opinion of Ethiopian great Haile Gebrselassie after watching first hand as Radcliffe struggled badly over the half-marathon distance in Vienna this month. The bookmakers seem to agree. You can get odds of 12-1 on the Briton winning gold on 5 August.
"The problem is adjusting mentally to getting older," says Ingrid Kristiansen, the Norwegian superstar who dominated female distance running in the 1980s as Radcliffe did in the last decade. "You try to train as you did when you were younger, but you need more time to recover.
"The problem I had as I moved into my late 30s - and I think Paula might have the same one - is that I looked back at the training schedule I had in my early 30s, and thought I could train as hard and often in my late 30s as I could then. I'm afraid you can't do that."
Radcliffe was hampered in Austria by antibiotics she was taking for a persistent bout of bronchitis. But her time - almost seven minutes outside her personal best - was far worse than she had feared possible.
"It felt like I was fighting harder than I should have been just to keep moving," she admitted afterwards. "I can't feel like that this summer.
"The danger is that it affects my confidence. Fitness-wise I could be starting from zero now and still be in shape for the Olympics, but it's more that I didn't feel good and didn't enjoy running. I'm worried about putting the training in and getting the races in that I want before London."
Recent history should offer her some comfort. Olympic marathons are seldom won by either the fastest woman in the field or in particularly fast times.
The gold in Athens, when a combination of injury and stomach problems forced Radcliffe to drop out with five kilometres left, was won by Japanese outsider Mizuki Noguchi in 2:26:20 - 11 minutes outside the record Radcliffe had set just 16 months before.
In Beijing it was the turn of unfancied Romanian Constantina Dita, again in a relatively stately 2:26:44. Dita's age when she claimed that surprise gold? Thirty-eight.
"I don't think the marathon at the Olympics will be a particularly fast one," Kristiansen told BBC Sport.
"It never is - but Paula is a classic front-runner. She used to do her best races when she went out by herself and could push and push. The problem she has now as she gets a little slower is that other athletes are quicker over the closing kilometres.
"Being part of the circus for so many years, pushing yourself so hard for so many years… the body starts to get worn out when you apply that much force to it."
What of Radcliffe's two children, Isla and Raphael? Can an elite athlete combine the demands of parenthood with the immense load of endurance training?
"Having two children isn't the issue for Paula," says Kristiansen, whose own career only really took off after the birth of her first son.
"She'll have someone who can take care of them when she needs to go for her training runs. The training element to each day is only two or three hours, and that's a short working day by anyone's standards.
"Most people work far longer hours. You also need time to rest, but what is rest? It's doing something else apart from training or your normal work. For me, I was resting when I was doing something with my kids. I hope it's the same for Paula.
"The good thing about being a mother is that you have something else to focus on apart from yourself and your training.
"The training part is very important when you're actually doing it. When you're out of training - between the two sessions each day - you have something else in your life to make you happy, rather than just sitting around waiting for the next training session."
Kristiansen retired in 1993, when she was 37 - a year younger than Radcliffe is now. Despite her many stellar achievements - world records at every distance from 5,000m up to marathon, four wins in the London Marathon, 10,000m gold at the World Championships - she too missed out on an Olympic medal.
"I was very disappointed after Seoul," she admits, referring to the incident when she tore her Achilles tendon in the 10,000m final.
"I really hope Paula can take the gold in her last Olympics so she doesn't have to feel like I did. I'm afraid she will feel the same, and it will be the same as me.
"But she can deal with it in the long run. The way I dealt with it was reminding myself that I'd had a lot of very good results in big races, and that I had three beautiful children. So I don't think about it any longer."
Radcliffe qualified for London 2012 with her encouraging 2:23:46 in Berlin last September. She still has time to get in better shape than that for August.
"I'm not giving up on it," she said this week. "I'll be fighting for gold and I don't think it's beyond me."
Sixteen years ago in Atlanta, Radcliffe came home a fine fifth in the 5,000m final. Four years later in Sydney she went even closer, denied a place on the podium by a last-lap sprint having led for much of the contest.
After the nightmare of 2004, Beijing was barely much better; a stress fracture of the left femur wrecked her preparations and bouts of severe cramp during the race left her back in 23rd.
"I hope she has a chance of a medal," says Kristiansen. "Four years ago I felt the same. But the marathon is getting harder and harder.
"There are so many girls coming up, and more countries than ever before are producing good distance runners. These girls are strong and they are fast. It will be difficult for her."