Austrian mathematician Anna Kiesenhofer sprang a major surprise at the Olympic Games by winning a gold medal in a women's Olympic road race on Sunday.

The 30-year-old national time trial champion Kiesenhofer, who holds a PhD degree in applied maths from the University of Catalonia and has also studied at Vienna and Cambridge Universities, took an early lead and was expected to run out of steam. But she valiantly held on to hold her own against a late surge by her rivals and bag the gold.

First, two-time world champion Anna van der Breggen, who was targeting back-to-back golds after winning in Rio, and then Van Vleuten went all out at the 2 km mark, but it turned out to be too late.

However, Van Vleuten did make up for a tragic crash at the Rio Games in 2016 with a silver medal. Italian Elisa Longo Borghini bagged bronze for the second consecutive Games.

"It's incredible, I couldn't believe it, even when I crossed the line," Kiesenhofer told the media.

"I planned to attack at kilometre zero and I was happy I could get in front. That is something I could not take for granted because I am not good at riding in the peloton.”

"I am happy that I was not too scared and I just went for it. I attacked and with the group we worked more or less together — it was helpful to have a group. I saw I was the strongest and I knew I had the climb before the long descent.

"I'm pretty good at descending so I got some more time and then it was just like a time trial to the finish."

Kiesenhofer shot through the 1km run-in with a smile and repeatedly looked over her shoulder as she cruised to win the gold in what could be one of the biggest upsets in the sport.