Usual suspects expected to dominate the track events

Analysis of the track events in the men's athletics programme:

100 metres

Usain Bolt thinks his defence of the blue riband sprint title could be the fastest race ever and that is certainly a possibility given the quality of the potential field.

The world record holder's most obvious challenger is training partner Yohan Blake, who benefited from Bolt's disqualification to claim the world title last year and beat his more famous compatriot at the Jamaican trials.

Blake ran the fastest time of the year (9.75 seconds) to win that race in Kingston and is the form runner in the Jamaican team with Bolt recovering from a hamstring problem.

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Asafa Powell has run more sub-10 second races than anyone ever and has the pure speed to win gold if he can only banish the psychological demons that strike when he competes on the biggest stages.

A Jamaican podium sweep is conceivable but a strong American trio, paced this year by 2004 Athens Olympic champion Justin Gatlin, will be keen to stake claims of their own.

Gatlin has hit top form again after returning from a four-year doping ban and won the U.S. trial ahead of Tyson Gay, the second fastest man of all time.

200 metres

This race could become the finest 200m in the history of the Games and it is all about two Jamaican training partners; defending Olympic champion Bolt and Blake.

If Bolt wins he will become the first man to win the event twice but it will not be straightforward.

Blake has caught the world's attention with 100m and 200m victories over Bolt in the Jamaican trials and some observers believe his explosive starts could give him the edge on the night.

Blake's time in Kingston of 19.80 was the fastest this year but it still lags behind Bolt's world record of 19.19, set in Berlin the year after his memorable win at the Beijing Games.

With Gay and Gatlin focusing on the 100m, America's challenge comes in the shape of Wallace Spearmon, disqualified for running outside of his lane in Beijing in 2008.

Frenchman Cristophe Lemaitre, who ran 19.91 in London in July, is Europe's best hope of a medal.

400 metres

American LaShawn Merritt, the year's fastest 400 metres runner, and Grenadian world champion Kirani James are joint favourites for gold in London.

Merritt, competing in London after winning an appeal over an IOC ruling to ban him from the Games as punishment for a 21-month doping ban, lost by three-hundredths of a second to the Caribbean runner at the 2011 world championships in South Korea.

The American, who has run the first and second fastest times this year, topping out at 44.12 in June's U.S. trials, is nursing his way back from a hamstring strain in Monaco in July.

If Merritt does win in London, he will join world record holder Michael Johnson as the only man to win back-to-back 400m titles. Johnson won gold in 1996 and 2000.

As well as James, Merritt could face competition from world junior champion Luguelin Santos of the Dominican Republic, whose 44.45 victory in Hengelo in May was a national record and made him the second fastest man in the world this year.

800 metres

Holding the world record, five of the seven fastest times of all time and the four fastest times this year over two laps, Kenya's David Rudisha will start as overwhelming favourite for gold.

The 23-year-old missed the Beijing Games through injury before being boxed in at the 2009 world championships and it will take something similar to stop him in London.

Among those trying is Ethiopian teenager Mohammed Aman, who is one of the few runners to have beaten Rudisha and ended the world champion's long winning streak last year.

Two other teenagers, Botswana's world junior champion Nigel Amos and Rudisha's compatriot Abraham Kipchirchir Rotich, have posted decent times this year but are likely to end up battling for the silver and bronze.

1,500 metres

Kenya's Asbel Kiprop, the world's fastest man this year, will have one thing on his mind in London; to win the 1500m properly.

The 23-year-old, who won a first world championships 1500m gold for Kenya last year, has often expressed his dissatisfaction at taking Olympic gold in Beijing after Rashid Ramzi was stripped of his title for a doping offence.

Kiprop is in great form, running the first sub 3:29 performance since 2004 with a time of 3:28.88 in Monaco.

A Kenyan clean sweep could be on the cards, with Commonwealth Games champion Silas Kiplagat, runner-up to Kiprop at the world championships in Daegu, and youngster Nixon Chebseba both in with a chance of a podium finish.

5,000 metres

Mo Farah will have already had a shot at Olympic glory in the 10,000m by the time this event starts but as favourite, the pressure will remain the same for the world champion bidding to become Britain's first long distance medallist.

Farah has won each of his four 5,000m outings this year, including a confidence-boosting early June 12:56.98 run in Eugene, United States, where he beat many of the world's best.

The challenging Ethiopian contingent will not include world record holder Kenenisa Bekele after youngsters Dejen Gebremeskel and Hagos Gebrhiwet edged him out with huge times in Paris.

Gebremeskel's world leading 12:46:81 was also the fifth fastest of all time with Gebrhiwet's the seventh fastest ever. The race itself saw the first 10 runners all cross the line in a quicker time than Farah has run this year.

The 18-year-old Isiah Kiplangat Koech looks like Kenya's strongest medal hope, while America's Galen Rupp - Farah's training partner - and veteran double world champion Bernard Lagat should not be discounted.

10,000 metres

European champion Farah will bid to become the first Briton to win a long distance gold in the men's 10,000m and settle a recent demon of having let victory in the world championships slip away in the final moments last year.

The Somali-born 29-year-old, who is enjoying a rising profile since moving to America in 2011 and switching to coach Alberto Salazar, will go up against Ethiopia's Bekele, who is gunning for an unprecedented third successive 10,000 metres gold.

The 30-year-old, who has three Olympic golds, five world championship titles on the track and both 5,000m and 10,000m world records, has built his own softer track to try and speed up recovery from persistent calf and knee problems.

He did not win a medal at the 2011 world championships but bounced back with the year's fastest time in Brussels.

Other contenders include Kenya's world bronze medallist Moses Masai and his fellow countryman Wilson Kiprop, who set the fastest time this year (27:01.98) and was promptly catapulted to the forefront of his country's hopes for a first 10,000m gold since Mexico in 1968.

Marathon

The first 29 on this season's marathon world list hail from either Kenya or Ethiopia, all with times of 2:07:28 or faster.

Wilson Kipsang is Kenya's best chance of repeating his late countryman Sammy Wanjiru's title in Beijing in 2008 - Kenya's first ever. Kipsang, 30, won the 2012 London marathon in the second fastest time of the year, building on two wins in 2011.

Fellow Kenyan, Abel Kirui, a two times world champion, is also a real contender.

The Kenyans will be challenged by Ethiopia's Ayele Abshero, who won in Dubai on his debut over the distance, beating a course record set by Haile Gebrselassie and setting the world's fourth fastest ever time. Ethiopia's Dino Sefir and Getu Feleke are both also strong runners.

3,000 metres steeplechase

Kenya's 2004 Olympic and double world champion Ezekiel Kemboi arrives in London with an assault charge hanging over him after a woman said he had attacked her with a knife when she declined his advances.

Kemboi's compatriot, 2007 world champion and 2008 Beijing Olympics gold medallist, Brimin Kipruto will join him with both expected to finish among the medals and continue Kenya's run of seven straight golds in this event.

110 metres hurdles

An intriguing battle between some of the fastest high hurdlers of all time looks set to elevate this most technical of events into the spotlight in London.

American Aries Merritt has hit his stride just at the right time with three sub 13-second times to snatch the favourites tag from China's Liu Xiang and world record holder Dayron Robles.

Liu will always be prey to the vicissitudes of injury, as happened at the last Games, but the 2004 Olympic champion has shown enough this season to suggest that if he gets it absolutely right, he will be difficult to beat.

Defending champion Robles has missed most of the season through injury and not hit anywhere his best form when he has run, while American Jason Richardson has apparently been inspired by his rather fortunate world championships win in Daegu last year.

400 metres hurdles

America's 33-year-old defending Olympic champion Angelo Taylor will bid to become the first man to win three Olympic 400m hurdles titles when he arrives in London.

Taylor will face competition from British hope and world champion Dai Greene and this year's fastest man Puerto Rican Javier Culson, who ran 47.78 in July and is aiming to become the first person from his country to win an Olympic medal.

Culson has won silver at the past two world championships and looked strong in this year's Diamond League series, winning ahead of Greene in both Paris and London.

4x100 metres relay

With the fastest man in the world in Bolt, world champion Blake and former 100 metres record holder Powell it is hard to look beyond defending Olympic champions Jamaica in the men's 4x100 metre relay.

Four years ago, the islanders won it in a record time and went even faster at last year's world championships with a run of 37.04. It will take a big effort from closest rivals the United States to deny them victory again.

The U.S. contingent, which includes Gay and Gatlin but is without the injured Walter Dix, have revamped their relay program. Central to it is not to drop the baton.

For three successive global meetings - the 2008 Olympic Games and the past two world championships - the U.S. have either dropped the baton or been disqualified.

4x400 metres relay

The Americans have won this event at the last seven Olympics and retained the title at the world championships in South Korea last year.

They needed a blistering last leg from Merritt to overhaul South Africa and Jamaica in Daegu, however, and those two teams as well as the Trinidad and Tobago quartet will fancy their chances of ending the long American hegemony.

20km walk

Russia's Valeriy Borchin was something of a surprise winner in Beijing four years ago but confirmed his status as the king of the shorter of the two walks by winning the world title in 2009 and retaining it last year.

Australia's Jared Tallent will be looking to upgrade the bronze he won at the last Games as part of his double challenge for gold in London

50km walk

Italy's Alex Schwazer will have to head off a Russian trio if he is to defend his Olympic crown in London.

Russia's Sergey Kirdyapkin, world champion in 2009, won this year's World Race Walking Cup with a leading time of 3:38:08 ahead of second-placed compatriot Igor Erikhin. Last year's world champion Sergey Bakulin completes the list of Russian contenders.