Japan's Junshiro Kobayashi claimed a surprise victory in the opening event of the ski jumping World Cup season in Wisla on Sunday, beating two-time Olympic champion and home favourite Kamil Stoch.

It was the 26-year-old's maiden top-level win and his first World Cup podium finish since November 2011.

Kobayashi is the first Japanese jumper to win a men's World Cup competition since Noriaki Kasai three years ago, although Sara Takanashi has won four of the last five women's big crystal globes.

"Of course I'm very happy about this result, but I'm also very surprised," Kobayashi told the FIS website.

"I had two very good jumps today and in the final round I also had good conditions."

Reigning Four Hills champion Stoch will be bidding to repeat his 2014 Olympic double gold in the Winter Games at Pyeongchang next year, but he had to settle for second in Poland despite soaring out to 129.5 metres on his second jump.

Kobayashi managed the same distance as Stoch over the two rounds, but edged to victory by only 2.3 points with a total of 260.5.

Austrian Stefan Kraft, who won two gold medals at this year's world championships and last season's overall World Cup crown, completed the top three, half a point further adrift.