Updated: Thu, 02 Aug 2012 13:10:00 GMT | By Sapa

PREVIEW: Athletics

We preview the start of the track and field events at London 2012...

Usain Bolt

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Two of the best-hidden features of the London Olympics are set to be revealed from Friday - the cauldron and the form of Jamaican sprinting star Usain Bolt.

Since being lit at the opening ceremony, the cauldron has controversially been kept inside an empty Olympic stadium, instead of being visible for all on top of the structure as in past Games.

Now it is set to light Usain Bolt home on his way to further sprint greatness, see the debut of double-amputee runner Oscar Pistorius and the farewell of pole vault queen Yelena Isinbayeva, as the showcase sport of athletics gets underway.

Bolt got a first-hand look at the cauldron as Jamaica's flag bearer at the opening ceremony and will take to the track midday Saturday in his quest to repeat his Beijing 2008 heroics of 100 metres, 200m and 4x100m golds, all in world-record time.

"This will be the moment, and this will be the year, when I set myself apart from other athletes in the world," Bolt said last week. "A lot of legends, a lot of people, have come before me, but this is my time."

Bolt remains the star attraction, even though he has found a formidable rival in countryman and training partner Yohan Blake.

He beat Bolt at the Jamaican trials in the 100m and 200m, is the season leader over both distances, and won 100m gold at the 2011 world championships when Bolt was disqualified for a false start.

Bolt says he has recovered from a hamstring problem, and with his world record of 9.58 seconds from 2009, he is the top favourite for the blue riband final at 2050 GMT Sunday to determine the fastest man in the world.

Blake and the US pair of Justin Gatlin - a 2004 gold medallist back from a doping ban - and Tyson Gay will be ready to exploit any of the superstar's mistakes or injuries. Jamaican Asafa Powell could also be in the picture if he controls his nerves.

The sprints will be about national pride, as Jamaica humiliated the US team by taking all six sprint golds in Beijing - highlighted by a women's 100m sweep led by Shelly-Ann Fraser.

South Africa's Pistorius, who is known as "blade runner" because of his carbon fibre prosthetics, will make his Olympic debut in the 400m heats on Friday.

He shone with four golds at the last two Paralympics and made his able-bodied, big-event debut at the 2011 world championships.

Pistorius was given the green light to compete with able-bodied athletes in 2008 by the Court of Arbitration for Sport, after the ruling athletics body IAAF declared him ineligible in 2007, saying the prosthetics gave him an unfair advantage.

"Being here is one of the biggest achievements in my career. I am proud of representing my country in the Olympics," Pistorius said.

Russia's glamorous Isinbayeva will aim to wrap the Olympic crowd around her finger one last time with a third straight women's pole vault gold, as she is set to retire after the 2013 world championships in Moscow.

She ruled pole vaulting for years and has raised the world record to 5.06m, 14cm above anyone else. But she has managed no medal at the past two world championships - no-heighting in 2009 - and is only fifth in the 2012 list.

"I had a very difficult time in the past. There was a lot of change in my life and then I came back to my first coach and my previous technique. It was really difficult, so winning in London would be very special for me," she said.

David Rudisha, meanwhile, leads a powerful Kenyan running squad and aims for gold in the 800m, which Olympic chief organizer Sebastian Coe won in 1980 and 1984.

"If it's not going to be a British athlete that wins the 800m Olympic title, I would love to see David win it," Coe told dpa. "I think he is a proper 800m runner."

Chinese hurdler Liu Xiang will aim to rebound from his 2008 injury heartbreak, while American Ashton Eaton will seek to confirm his recent decathlon world record.

Team GB's hopes rest on heptathlete Jessica Ennis, 400m hurdles world champion Dai Greene and 5,000m world champion Mo Farah.

Marathon runners will not see the cauldron, but will instead have a special London experience with a postcard course starting at The Mall and featuring Buckingham Palace, Big Ben, Tower Bridge and other landmarks of the British capital.