The favorite is Michael Johnson, 32, whose face (or, more accurately, whose flying golden feet) became famous at the last Olympics, where he was the first man ever to win gold in both the 200 and 400 meters. He holds the world records in both events and hopes to repeat his double glory at the Sydney Games this coming September. The challenge comes from a relatively new kid off the blocks, Maurice Greene, who will turn 26 the day of the race. His 9.79-second world record in the 100 has earned him the unofficial title of world’s fastest human. Last year “Mo” became the first sprinter ever to win both the 100 and 200 meters at the world championships.

The two last went head to head more than two years ago. Deep in a post-Olympic slump, Johnson ran almost a full second slower than his record time, and the upstart Greene whupped him. They were scheduled to race again twice last summer, and Johnson pulled out both times–once to attend his grandmother’s funeral and once because of a minor injury. Greene began to accuse Johnson of ducking him. “He can run whenever he wants, but it just seems he wants to run when I’m not in the race,” says Greene, who is equal parts amiable and cocky. “All I’ve been saying is, ‘Let’s give the fans what they want to see’.”

Johnson, who is bright, supremely confident and more than a little prickly, was incensed by Greene’s disrespect. “I was raised to have dignity, not to be a trash talker,” he says. “But it just got to the point when I could no longer hold my tongue.” When he finally let go, John-son showed the same kick with his comments that he does with his feet. “He should show a lit-tle class,” Johnson said. “But he knows any time he mentions my name, he gets his name in print.”

Johnson doesn’t think Greene’s name belongs with other Olympic sprinting threats like Ato Boldon from Trinidad and Tobago or Frankie Fredericks from Namibia. “What’s [Greene’s] personal best–19.8?” sneers Johnson, who set the record, 19.32, at the ‘96 Olympics. (Greene’s best is actually 19.86.) “He’s a great 100-meter runner, but so far he hasn’t proven he can be really good at the 200. So go ahead, build the race up all you want, but don’t expect me to get excited about the guy.”

Greene’s team is quick to point out that while Maurice may not have approached Johnson’s record time yet, neither has Michael since he set the mark in Atlanta. Indeed, with the exception of his stirring world-record effort in the 400 at last year’s world championship, Johnson’s biggest post-Olympic successes have been in TV ads for everything from soft drinks to Internet technology. Meanwhile, Greene has been racing anywhere and everywhere, trying to erase the memory of a futile ‘96 season in which, hampered by a leg injury, he didn’t get past the 100-meter quarterfinal at the Olympic trials. “I still have an empty place in my heart,” Greene says. “I’m running to redeem myself.”

This is the one season in four when track and field goes prime time–and this week, finally, the one thing that counts is performance. Places on the U.S. Olympic track-and-field team are earned in a single competition, with no exceptions for injury or reputation. Through the years, the American trials have offered some memorable matchups–long jumpers Carl Lewis vs. Mike Powell, sprinters Gail Devers vs. Gwen Torrence, decathletes Dan O’Brien vs. Dave Johnson–as dramatic as anything that happens at the Olympics.

The top three finishers earn Olympic berths, so both Johnson and Greene are almost certainly bound for Sydney in the 200, as well as, respectively, in the 400 and 100. But their 200-meter showdown is a battle of both legs and mind, and a trials victory on Sunday could prove a big boost toward the highest podium in Australia. “It will be a really big advantage to win,” says Greene.

The war of words ends Sunday. Greene will need to explode out of the starting blocks and force Johnson to chase him from behind. If, instead, Johnson gets out fast, the race is all but over. Nobody runs the curve better than he does, and nobody catches Michael Johnson down the stretch–no matter how fast he talks.