Kapalua - Lance Armstrong crashed and hit his head with about a mile to go in the mountain-bike ride and faded from second to 23rd in the running leg of the XTERRA World Championship, with Austria's Michael Weiss finishing strong to win the off-road triathlon on Sunday.
"I just crashed, crashed as we were coming back," the 40-year-old Armstrong said.
"I hit it harder than I thought because I stood there for a while taking inventory, trying to remember my name. That probably took a little out of me, obviously, took a little out of me standing there for a minute or so. I have never hit my head that hard before."
Weiss completed the mile ocean swim, 18.3-mile mountain-bike ride and 6.1-mile trail run in 2 hours, 27 minutes. South Africa's Dan Hugo was second, 33 seconds back, and Eneko Llanos of Spain was third.
Armstrong finished in 2:36:59.
The seven-time Tour de France winner, fifth in the XTERRA USA Championship in Utah last month in his first triathlon in 22 years, faded badly in the run on a day where the temperature reached 90 degrees.
"Everybody paid the price on the run, even Weiss, who can run," Armstrong said.
"It's just a damn hard course, a death march."
Weiss passed Armstrong about 14 miles (22 kilometers) into the bike leg.
"I can just say it is an honor for me to race Lance," said Weiss, a 2004 Olympian in mountain biking for Austria.
"I outrode him on the bike, from my point of view."
Conrad "The Caveman" Stoltz, the South African who won his fourth title in the event last year, dropped out on the third mile of the run.
Lesley Paterson of the United States won the women's race.