Triathlons aren't supposed to be determined this way. They are meant to separate the strong from the weak, the determined from the soft, over a couple of grueling hours. They don't normally come down to the final 200 meters in a sprint for the finish.

Yet when Australian Loretta Harrop -- who led Wednesday's women's Olympic triathlon after the swim, then after the bike, then during nearly the entire run -- looked over her shoulder as she struggled down the final hill, heading to the finish line along the coast of the Aegean Sea, there could be nothing but shock. Kate Allen -- a native Australian representing Austria, an athlete most of the top women in the race had never heard of -- was right there. A moment later, Allen was gone, on her way to deeming her performance "amazing, a total surprise."

Allen took the gold medal in an upset that was stunning not only because of who won, but how she did it. Harrop had worked all through the hot, sunny morning to separate herself from three strong Americans -- Susan Williams, Sheila Taormina and Barb Lindquist -- and had done so comfortably. But Allen made sure during the 10-kilometer run, which she entered nearly three minutes behind Harrop, that people began to learn about who she is.

"It wasn't till the last 200 meters that I saw it was possible," Allen said.

There, Allen passed an overwhelmed Harrop -- who professed to be pleased afterward, though she didn't crack anything close to a smile -- and ran on to the finish, where she stopped, put her hands skyward, and then let them fall back on her head, a what-have-I-done expression of disbelief. Her winning time over the 1.5-kilometer swim, 40-kilometer cycle and 10-kilometer run was 2 hours 4 minutes 43.45 seconds.

Harrop was second, nearly seven seconds behind. Williams, the least heralded of the American athletes, won the bronze when she crossed the line 25 seconds back, an accomplishment that looked unlikely when she crashed her bike on the first lap around the demanding, hilly cycle course.

The medal was sweet for Williams, a native of Springfield and graduate of Lake Braddock High, for several reasons. She missed the 2000 Olympics when she unexpectedly got pregnant. In honor of the timing, she named her daughter Sydney.

"I like to say she's my gold medal from that race," Williams said.

Coming into the race, the Americans' hopes seemed to rest more with Lindquist, the top-ranked triathlete in the world, or Taormina. And in the early going, those predictions made sense. Harrop and Taormina both finished the swim in 18:37, fastest in the field, with Lindquist two seconds behind. Those three shot off on their cycles, with Williams -- 25 seconds slower in the swim -- in pursuit.

Then, the fall. Williams stormed down a steep slope, and took a turn a bit too wide. As she braked, her rear tire skidded out from under her, just slightly.

"Oh my goodness," Williams said she thought. "I am crashing in the Olympic Games. This is not good."

Eventually, Williams ran into a padded wall that lined the course, and righted herself relatively quickly. Lindquist, just ahead, noticed. Figuring she had a better chance of cycling fast in tandem with Williams, she waited.

"For me to ride by myself," Lindquist said, "I would've just been waiting for the next group to catch me."

Harrop, though, ended up riding largely by herself. When it was time for the run, she had opened a 20-second lead over Taormina, with Williams and Lindquist close behind. Cycling alone, however, "made it a tough day at the office," Harrop said.

So it looked like at least two Americans would medal, and a sweep was possible. But lurking back, tied for 10th after the bike leg, was Allen.

"I haven't heard that much about Kate," Lindquist said. "I don't know much about her at all."

Turns out Allen grew up about 12 miles outside Geelong, in southern Australia, and after running as a young girl, then turning to gymnastics, she went to college "and partied a lot, and had a good time." Athletics fell out of her life.

Eight years ago, though, she picked it back up. She met her husband, an Austrian, while working in Europe, and stayed there. She started racing, but stayed almost exclusively in Europe. When she travels back to Australia for three months every year, she trains but doesn't compete.

So that left her way under the radar at the start of the race, and kept her under it when she started to make her move. Running, she said, has long been her strength, and she covered the 10 kilometers in 33:48, the fastest split in the field by 1:08. And she overtook Harrop in full view of the spectators who crowded around the finish line.

"Talk about a made-for-television finish for triathlon," U.S. Coach Gale Bernhardt said. "That was it."

Unfortunately for the United States, Taormina wasn't part of it. She did her best to stay with Harrop, but while running the final lap, her calves and quadriceps cramped. She did well just to finish, which she did in 23rd place, and shrugged as she crossed the line in her final race before retirement.

Lindquist, third after the bike, couldn't keep up either, and eventually placed ninth. The American hopes were left to Williams, who didn't disappoint. Eight years ago, she made a decision to pursue triathlon and leave behind her quest to become an astronaut. She plans on retiring from professional triathlon after next year. But in the moments after the race, with the bronze medal draped around her neck, there was no question she made the right choice.

"I am thrilled," Williams said. "It's a dream come true for me. I was the dark horse to even make the team, and here I am."

Susan Williams, right, celebrates her bronze medal finish with U.S. teammate Barb Lindquist. Kate Allen won the gold for Austria in an upset.