1. Missy Franklin
Swimming (United States)
Swimming's worst kept secret. The 17-year-old already has three world championship gold medals in her locker (alongside silver and bronze) and a world record - last year she became the first women to set a new mark since bodysuits were banned. In London she will compete in seven events and has hopes of winning a medal in all of them, which would at a stroke make her the most successful US woman at a Games - Nathalie Coughlin holds the record with six. Franklin - Missy is short for Melissa - is 6ft 1in and has size 13 feet, so has the tools. Her duel with the Italian Federica Pellegrini in the 100 and 200m freestyle will be riveting, while it will take a mighty swim to deny her at least one of two backstroke golds. Whatever happens in London, her next stop post-Games will be a return to school in Colorado.
2. Kohei Uchimura
Gymnastics is the archetypal Olympic sport, in that it goes unnoticed outside of the aficionados until Games time whereupon it repeatedly throws up some of the most eye-catching performances. Few in London are likely to better Uchimura. Super-mura, a 23-year-old from Nagasaki, has not been beaten since the last Olympics. If, and it is not reckoned to be much of an if, he wins all-round gold, then he will have completed the perfect Olympic cycle. Uchimura, who first took up the sport aged three, won the 2009, 2010 and 2011 world titles, and by margins that in gymnastics were huge. "It's crazy," said Sam Oldham, who will compete for Britain. "He's too good." Four years ago in Beijing a teenage Uchimura took a couple of silvers; expect alchemy at the North Greenwich Arena.
3. Laura Trott
Cycling (Great Britain)
Another who has world titles to her name. If Trott delivers what many expect she will be a star. Bubbly, personable, talkative, the 20-year-old has it all. Picked out in a talent-spotting visit to her school, Trott has risen rapidly. She won her first world title last year in the team pursuit, but it was in Melbourne in April that she gave an opposition-crushing demonstration. First she was part of the three-strong pursuit team that broke the world record to win gold and then went solo to take the omnium. New for the 2012 Games, the omnium consists of six events including the crowd-pleasing elimination race – the last rider is knocked out after every few laps – at which Trott is adept. Dave Brailsford, British cycling supremo has picked her out for stardom. He's rarely wrong.
4. Ashton Eaton
Track & field (US)
Eaton is an all-round athlete set to win the admiration of a London crowd much as Bob Mathias, the all-American hero did en route to gold in 1948. The 24-year-old broke the world record – once held by Daley Thompson – just to qualify for London. It was only three years ago that Eaton finished 18th in the world championships but his improvement has been dramatic. He took silver in Daegu last year and then became only the second man to break the 9,000 point barrier in the trials.
5. Helen Jenkins
On the morning of Super Saturday, the middle weekend of the Games, Jenkins will run, swim and cycle around Hyde Park and could be the star of a star-studded day. Jenkins is not even Britain's best known triathlete – the Brownlee brothers jostle for that – but she is mighty good. So good that the two other members of the team are there as domestiques, to help her to victory. Jenkins finished 21st in Beijing, but the 28-year-old, coached by her husband Marc (they married in Disney World after Beijing) is the woman to beat, entering the race as No 1 in the world.
6. James Magnussen
There are fears within Team Australia that this could be their worst week in the pool since Atlanta 96. A lot then rests on Magnussen, but he has broad shoulders – literally and figuratively. The 21-year-old from the New South Wales coast is everything you would expect in an Aussie sportsman – bronzed, confident bordering on the cocksure and an outstanding talent. The Missile is the best speed swimmer Australia has produced and will go for double gold in the 50 and 100m freestyle as well as leading the charge for freestyle relay gold. He has also stated his desire to break Cesar Cielo's 100m world record en route to the podium.
7. Anthony Joshua
There's a good feeling around Britain's boxers, men and women. Natasha Jonas will seek to create history in the women's event, but it is the mighty Joshua who could end Britain's Games on a high. The super-heavyweight division is settled on the final afternoon, just before the closing ceremony, and Joshua is fancied to be involved. That would be some achievement for a 22-year-old who has only been fighting for four years. Last year he went to the world championships in Azerbaijan ranked 46 in the world but reached the final after beating Roberto Cammerelle, the No 1 and Olympic champion en route. Joshua, 6ft 6in and 1 7 stone, won silver. Barry McGuigan, for one, has forecast a bright future for the Londoner.
8. Leandro Damiao
The playing fields of London have already provided the striker with two of the greatest moments of his fledgling career. It was at the Emirates a year ago he made his Brazil debut in a friendly against Scotland and that was followed by his first goal for his country at Craven Cottage against Ghana. Brazil take the Olympics seriously – they are led by national manager Mano Menezes – and Leandro is earmarked for a pivotal role. A long-time target for Tottenham among others, the 22-year-old is a 6ft 1in combination of power as well as more traditional Brazilian skills.
9. Katherine Grainger
At 36 and competing in her fourth Olympics, Grainger might seem an odd choice for this list but should she, and partner Anna Watkins, win gold at Eton Dornay it will be one of the British stories of the Games. In 2000 Grainger won silver, followed it with another in 2004 and four years ago also rowed to second place in Beijing. This then is her last chance, and curiously enough her best chance. Grainger and Watkins are the best scullers in the world – they have won the last two world championships. They have not been beaten since first being paired up in 2010. Silver is simply not an option.
10. Qiu Bo
To win gold in the Aquatics Centre all Tom Daley has to do is finish ahead of Qiu, the teenager known as Mr Full Mark for his phenomenal record off the 10m board. There is one hope for Daley – three years ago Qiu, the favourite, blew his last dive at the world championships to hand the gold to the 15-year-old Daley. But since then the 19-year-old has cemented his standing as the stellar performer among an outstanding generation of Chinese divers. The son of two factory workers, he used to practice by leaping off a trampoline on to a pile of cushions. His stocky build is unusual in the sport, but then so his is ability. In last year's world series in Beijing he was awarded 25 perfect 10s (Chinese divers tend to receive high marks at home). Nevertheless, watch and admire what could come close to sporting perfection.
Outsiders from Games gone by
Won gold for swimming, 2000
Arriving at his home games with local enthusiasm but little track record behind him, the 17-year-old from Sydney won a remarkable three golds - with world records in each - and two silver medals. He was rewarded with carrying the Australian flag at the closing ceremony.
Won gold for boxing, 1960
Despite an impressive amateur record, Cassius Clay was still just a talented 18-year-old when he arrived in Rome to fight for the light-heavyweight gold medal. The speed and confidence which were to make him a legend as Muhammad Ali were in evidence, and he comfortably beat Zbigniew Pietrzykowsk for gold.
Won gold for gymnastics, 1976
The 14-year-old Romanian gymnast Comaneci arrived at the Montreal Olympics without much attention. She changed her discipline forever, though, recording the first perfect 10.00 score in Olympic history on the uneven bars. She went on to win two more golds, one bronze and a silver in 1976 alone.
Won gold for 1500m, 1988
The expectation in Seoul was that either Steve Cram or Peter Elliott would win gold for Britain, their third consecutive victory in the 1500m. But Peter Rono, a 21-year-old from the Rift Valley in Kenya, surprised everyone and became the youngest ever winner of this event. He never won a major race again.