EUGENE, Oregon - Double world champion Tyson Gay and a host of the world's leading performers will be vying for coveted Olympic spots at the United States selection trials which start on Friday.

Sprinter Tyson Gay of the US speaks at a news conference in New York, May 29, 2008. [Agencies]

A strict format that allows only the top-three finishers per event to qualify for Beijing leaves open the possibility of major upsets at the 10-day meet, but the US team will still head to China confident of completing an impressive medal haul.

"This will be our best Olympic Games... men and women," US Olympic women's coach Jeanette Bolden told reporters after surveying the field for the trials.

"It will have a nice mixture of both veteran and up-and-coming athletes."

Gay, Olympic and world 400 metres gold medallist Jeremey Wariner, women's 200 metres world champion Allyson Felix and 400 metres favourite Sanya Richards are all expected to shine on the University of Oregon's Hayward Field track.

The women's 100 metres with Felix and former world champions Lauryn Williams and Torri Edwards is likely to be just one of many intense and classy encounters.

If the favourites survive the trials, American athletes could head to Beijing for the August Games confident of sweeping Olympic medals in both the men's shot put and 400 metres hurdles.

"It's brutal," said two-time Olympic shot put silver medallist Adam Nelson, who will be challenged by world champion Reese Hoffa and indoor winner Christian Cantwell.

LAGAT'S FIRST

The double bid of world 1,500 and 5,000 metres champion Bernard Lagat is also an interesting prospect.

Twice an Olympic 1,500 metres medallist for his native Kenya, Lagat will be aiming for his first Games in a US vest, having become an American citizen in 2004.

The bar could also be raised in the pole vault as the 2008 world leaders and American record holders Brad Walker and Jenn Stuczynski headline the men's and women's events.

Few, though, will attract more attention than Gay, who begins his competition on Saturday.

"In 2004 it was about trying to make the team," the 25-year-old sprinter told Reuters.

"Now it's more about winning the trials, running fast and watching everything come into order."

He is the favourite in both the 100 and 200 metres but knows any misstep can sidetrack dreams of competing at his first Olympics.

"Every Olympic year guys are always running fast," he said.

Gay discovered just that in New York's Reebok Grand Prix last month when Jamaican Usain Bolt roared away from the field to win the 100 metres in a world-record 9.72 seconds.

"I was a little down about that, but I had to refocus to make sure of my main goal -- to win," Gay added.