BOISE, Idaho -- Tara Whitten led a Canadian sweep of the first three spots in the Exergy Tour prologue Thursday after American gold medalist Kristin Armstrong fell and likely broke her left collarbone during the two-mile stage.
Armstrong, who lives in Boise and was the last of 103 riders to start, fell hard at the turnaround, putting her London Olympic hopes in doubt.
Whitten, an experienced track rider, finished in 4 minutes, 9 seconds.
She finished just ahead of Gillian Carleton. Clara Hughes was third.
Armstrong, from Boise, finished 8 seconds behind Whitten in 13th place.
The American was crying and holding her left shoulder after she climbed off her bicycle. Her husband, Joe Savola, said she would have surgery Friday and would abandon the Exergy Tour, but hasn't ruled out competing in London if she's chosen for the team.
USA Cycling will make its selections June 15.
"She's the fastest time-trial rider in the world," Savola said. "She would have broken 4 minutes. She was flying, she was taking a chance."
After the race, Whitten told The Associated Press that sharp turns on the course forced her to slow at several sections, including the turnaround.
"There were some technical sections where I thought I lost a little time," she said.
Whitten races for Team TIBCO, a California-based team that had $120,000 worth of bikes and equipment stolen from the team trailer a day before the race. All of the bikes were recovered.
"It was definitely not a good feeling (Wednesday) morning when we came down to breakfast," said Whitten, whose road bike was among those taken. She was all smiles after winning the stage just a day later.
Following the race, Whitten, Carleton and Hughes were shocked and saddened to learn at a news conference the extent of Armstrong's injuries.
Hughes said she fell on the same turn as Armstrong during the warm-up for the race. She said she slowed for the turnaround during the race, but only a little.
"My easy is probably on par with other people's hard, so I don't think I lost any time," Hughes said.
Armstrong was competing for a spot on the time trial team at the London Olympics with two other U.S. riders, Evelyn Stevens, of Boulder, Colo., and Amber Neben, of Lake Forest, Calif.
Stevens finished fifth Thursday, while Neben was eighth.
Steve Johnson, chief executive officer of USA Cycling, suspected the worst after watching Armstrong fall to the pavement near the Boise depot, the location of her wedding to Savola in 2007.
"It is amazing that she was able to get back on her bike and finish only 8 seconds off the pace," he said in an email.
The Exergy Tour continues Friday, with a 76.7-mile ride through Idaho wine country near the Snake River.
The five-day event concludes Monday.