World record holders Michael Johnson and Maurice Greene will duel for pride and Sydney Games berths in the US Olympic trials, which begin in California tomorrow.

After months of hype and barbs, Johnson and Greene will finally decide who is best at 200 metres on Greene's 26th birthday, July 23rd, during 10 days of cut-throat trials already filled with interesting sub-plots.

Can Marion Jones, for example, win both women's sprints and the long jump to launch her quest for five gold medals in Sydney? Will her husband, CJ Hunter, claim the men's shot-put title as he did at last year's world championships?

The top three finishers in each event will qualify for Sydney.

"The trials are the biggest meet of my life right now," said Greene, who has never run at the Olympics despite his two world championships and a world record time of 9.79 seconds in the 100 metres. He hopes to win the 100 metres before clashing with Johnson in the 200 metres.

Johnson, meanwhile, has his sights set on turning trials victories in the 200 and 400 metres into stepping-stones on the way to becoming the first athlete to achieve repeat victories in those events at the Olympics.

"People don't come to see us just to see the stars give lacklustre performances," Johnson said. "They're coming to see great races and I plan to give them that."

Neither athlete, it seems, wants to hold back for a rematch in Sydney. "I can impart all of the information that I want, it is not going to make any difference," said John Smith, Greene's coach. "No matter what I tell them. No matter what Clyde Hart (Johnson's coach) tells Michael, we are both going to be sitting there praying that they survive, whatever they put out there." World 200 metres women's champion Inger Miller is hoping to generate a similar showdown with Jones at both 100 and 200 metres.

Twice world 100 metres champion Jones, who crashed out of last year's world championships in the 200 metres because of back spasms, said:

"The trials are pretty much do or die. If you don't make the team, your season is over."

Then there is Jackie Joyner-Kersee, making a comeback at the age 38. Will she be a threat to Jones in the long jump? Can she make her fifth consecutive Olympic team?

Will legally blind Marla Runyan overcome her handicap and a recent injury to spin a heart-warming 1,500 metres story and will past Olympic champions Allen Johnson and Gail Devers hurdle their way to new acclaim?

The answers will come as rapidly as a sprint and as slowly as a walk as the Americans decide on their Olympic team.