Veteran American Kristin Armstrong claimed a third consecutive road time trial gold to deny former Russian doper Olga Zabelinskaya what would have been a controversial triumph on a rain-soaked course at the Rio Games on Wednesday.
Double London medallist Zabelinskaya, who served an 18-month suspension for a banned stimulant and was only cleared to compete in Rio last week, had set the fastest time with only Armstrong still on the 29.7km course.
Armstrong had been quickest over the opening 10km and then produced a searing late burst on the Grumari circuit to clock in 44 minutes 26.42 seconds the day before her 43rd birthday.
Dutch rider Anna van der Breggen added a bronze medal to her gold in Sunday's road race as she finished 11 seconds back.
Armstrong retired from the sport in 2009 to start a family but returned to win in London before again calling it a day.
After a three-year break and three hip surgeries she made another comeback last year with an eye on Rio.
No wonder she cried with joy at the finish, having picked herself up after collapsing in exhaustion on the soaked tarmac.
"It's amazing, I don't know if it has hit me yet," Armstrong told reporters after hugging her five-year-old son and holding up a sign that said "USA STRONG".
"This has been the most difficult journey. I took time off. The mind gets tired. So when I came back I was focused on Rio and it's been difficult because I've had some poor performances over the last six months."
Armstrong needed all her vast experience to tackle two tough climbs in weather more akin to a rainy day in Flanders.
"When I looked out of the window at 4am I thought, 'Oh no!' But I had two choices, get nervous, or say I'm the most experienced person out here and just attack it."
Zabelinskaya, who finished third in the road race and time trial in London, was also in tears at the end, having celebrated prematurely thinking she had done enough to win.
Her place in Rio was in jeopardy until days before the Olympics after the International Olympic Committee attempted to ban all Russians with a doping past. The Court of Arbitration for Sport (CAS) then said that ban was unenforceable.