EUGENE, Oregon - Tyson Gay expects a dog fight in the men's 100 metres, Allyson Felix is eyeing a spot in the women's 100 as well as her favoured 200 and Ashton Eaton wants to make history in the decathlon.

Welcome to the high intensity, tension-fuelled U.S. Olympic athletics trials, where through cut-throat competition America will select its team for the London Games.

Over 11 days beginning on Thursday, only a top-three finish and the Olympic qualifying standard matter. Otherwise, you stay home.

"Our Olympic trials are one of the most difficult events to deal with in all my history of sports, and I've been in a lot of locker rooms in a lot of sports," acclaimed U.S track coach Bob Kersee told Reuters.

"We leave people home that could make any other Olympic team outside, in the past, maybe East Germany or Russia and Jamaica now."

That statement rings true particularly in the sprints, and the sub-plots at this year's trials in the athletics-friendly college town of Eugene are as numerous as the track and field events themselves.

The highlights:

Men's 100 metres

A test of former world champion Tyson Gay's surgically repaired right hip when he comes up against 2004 Olympic champion Justin Gatlin, Olympic bronze medallist Walter Dix and America's covey of fast runners.

The competition is only Gay's second in a year, Gatlin is back at full strength after missing four years for a doping ban and Dix, who has been hampered by leg problems, has plenty to prove after running poorly in his last outing.

The reward for the three quickest? Challenging Jamaican world record holder Usain Bolt and world champion Yohan Blake in London.

Women's 200 metres

Maybe one of the most competitive races at the trials with three-times world champion Allyson Felix challenged by Sanya Richards-Ross, the former 400 metres world champion who owns the year's fastest times in both the 200 and 400 and, perhaps, 100 metres world champion Carmelita Jeter. Collegian Kimberlyn Duncan can not be discounted either.

Decathlon

This is a true heavyweight showdown with the Olympic champion Bryan Clay and world champion Trey Hardee competing against the current world indoor record holder Ashton Eaton, who believes a world record is within his grasp.

Dan O'Brien's 1992 American record of 8,891 points is certainly a distinct possibility.

Women's 100 metres

World champion Carmelita Jeter is the fastest female sprinter in the world this year but she is desperate to snap a string of recent losses. the 2005 world long jump champion-turned sprinter Tianna Madison and Felix, who clocked a personal best over the distance earlier this year, are among Jeter's biggest threats.

110 hurdles

Like the decathlon, this event features the best of the best as world outdoor champion Jason Richardson, world indoor champion Aries Merritt and Olympic bronze medallist David Oliver, the U.S. record holder, all involved.

Men's 200 metres

Wallace Spearmon has unfinished business at the Olympics after his Beijing disqualification four years ago for a lane violation when he finished third.

Walter Dix, the 2008 Olympic bronze medallist, has entered but whether he runs and how effective he will be remains uncertain until after his participation in the 100 metres.

Gay is not bothering to race at all with Gatlin to decide after the 100.

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