Kokoro Fujii won the men's bouldering competition at the season opener of the IFSC Climbing World Cup tour on Saturday.
The 24-year-old Fujii, who finished second in the overall World Cup rankings last season, earned 100 points for having the least number of attempts at Haslital Climbing Gym to finish ahead of Russia's Aleksei Rubtsov.
Japanese compatriots Keita Watabe and Rei Sugimoto were third and fourth, respectively.
"I'm really surprised because I wasn't feeling on top form," said Fujii.
"If you ask me to complete the boulder problem successfully again I don't think I can do it. I focused and tried to get it done in one attempt."
In the women's bouldering won by Britain's Shauna Coxsey, who completed all four routes, Miho Nonaka of Japan cleared one and finished third.
Last summer, the International Olympic Committee agreed to add climbing, along with baseball/softball, karate, skateboard and surfing, to the sports program for the 2020 Tokyo Olympics.
At the Tokyo Games, climbers will compete in three disciplines — boulder, lead and speed — and medals will be given based on overall scores.