TOKYO • Austrian mathematician Anna Kiesenhofer upstaged a heralded Dutch quartet to win a shock gold in the women's Olympic cycling road race yesterday.

The 30-year-old national time-trial champion, a graduate of Cambridge University, held her nerve after a long breakaway that the main peloton never managed to reel in.

Annemiek van Vleuten took the silver, while Italian Elisa Longo Borghini bagged bronze for the second consecutive time.

In a dramatic finale to a long day's ride, the peloton reeled in France's Juliette Labous and, with under 4km to go, the gap to Kiesenhofer was cut to under three minutes.

First, two-time world champion Anna van der Breggen, who was targeting back-to-back golds after winning in Rio de Janeiro, and then fellow Dutchwoman van Vleuten cut loose at the 2km mark, but it was too much too late.

Kiesenhofer was allowed to go solo on the approaches to the Fuji International Speedway circuit with around 40km remaining as the favourites failed to organise a proper chase, seemingly unaware of what was happening ahead.

The leader, who is not even part of a professional cycling outfit, shot through the 1km run-in smiling and constantly looking over her shoulder in full knowledge that the gold was hers in a massive upset of the form book.

Drenched in sweat, she collapsed to the ground after coming through the finish line, screaming in delight, hands on helmet in near-disbelief.

So great was Kiesenhofer's 1min 15sec-winning lead that van Vleuten failed to realise she was only in second place, celebrating as though she had won as she crossed the line, before exclaiming: "I was wrong."

Kiesenhofer is the first Austrian to win an Olympic road race medal and the first to win an Olympic medal in any cycling discipline in 125 years.

Silver was some consolation for van Vleuten, who crashed spectacularly in Rio five years ago with a gold in sight.

But the Dutchwoman, competing in this race for the third successive Olympics, admitted it was a disappointing finale as they got their wires crossed in unbelievable fashion.

Lacking the aid of team radios, which are not allowed at the Games, the team miscalculated their positions, said van Vleuten.

"I don't think anyone wrote her (Kiesenhofer) down. I don't know her. How much can you do wrong, if you don't know someone?"

"We thought we were doing it right... and we thought we were driving for the gold."

AGENCE FRANCE-PRESSE, REUTERS