Frenchwoman Anne-Caroline Chausson held her nerve in a dramatic, crash-marred final to win the Olympic Games' inaugural BMX gold here Friday.
Her compatriot Laetitia le Corguille finished second to take the silver with Jill Kintner of the United States taking the bronze.
Britain's Shanaze Reade was in silver medal position on the last bend but in yet another setback for the 19-year-old, two-time world champion, she clipped Chausson's back wheel and crashed out of the race.
It was the last competitive race for the 30-year-old Chausson, a multiple world champion in mountain bike who came back to her first love of BMX two years ago after it was included on the Olympic programme.
"It's been a long two years of hard work, but this is definitely my last race," said Chausson, who stopped BMX when she was 13 years old to take up mountain biking.
"To finish as Olympic champion, having applied all the things we've worked on in training for this over the past two years is just amazing."
From the three semi-final runs Chausson was only third fastest overall, meaning she began the one-run final with New Zealand's Sarah Walker and Reade for close company.
But she admitted that had been part of her plans.
After launching off the steep ramp Reade and Chausson broke clear of the field as Walker, like several riders during the unforgiving rounds, crashed to see her medal chances hampered.
The two frontrunners broke further ahead of the field going into the final bend, with Chausson pulling slightly in front of 19-year-old Reade.
Disaster struck for Reade when her front wheel appeared to clip the back wheel of Chausson, and she came crashing down. It was her third crash in two days of racing, and left her with a suspected hand injury.
"She must have taken the bend too tight, and then I felt her clipping my back wheel," said Chausson, who had been unaware she was in a duel for the gold medal.
It was also Reade's first defeat in a final since she was 16, but she has promised to come back to fight for gold at London in 2012.
"I guess they say you learn the hard way, and today I've learned the hard way," said Reade.
"I am hurting. I think I broke my hand as well."
She added: "I put abolsutely everything into this, everything from the age of ten. But I'm an athlete, I'll come back stronger in London and show everyone what I'm made of."