Climbing in front of around 5,000 fans in the Czech capital, 20-year-old Lee got off to a blistering start as he managed to reach all four zones in the round.

He followed it up with four tops to clinch his first World Cup medal.

"I can't believe it, I'm just so happy," said Lee.

"Thank you all for the support."

Home favourite Adam Ondra also reached all the targets but took more attempts to do so and had to settle for silver as a result.

The slab section of the wall proved to be the difference maker as Ondra needed three attempts while Lee got it on the first try.

"It's been so nice to be back on the circuit, especially in my home country," Ondra said, after reaching his 15^th World Cup podium in the boulder discipline.

"It's been 13 years since the last World Cup event in Czechia, and the only one I participated in was in my hometown of Brno, when I was 16 and I barely missed the final, it was so frustrating, so this is a good revenge!"

Bertone pulled off an upset in the women's event as she beat Olympic champion Janja Garnbret of Slovenia to gold.

Both hit three tops and four zones but two fewer attempts on both from Bertone meant she topped the standings.

They were joined on the podium by Bertone's compatriot Cohaut Flavy who scored two tops and three zones.

Bertone's victory was made all the more remarkable following her semi-final performance as she scraped through in sixth, the last qualifying position.

The World Cup is set to continue with the sixth stop of the season from June 9 to 11 in the Italian town of Brixen, with boulder competitions scheduled once again.