The field included 13 of the top 20 riders in the world but it was Zorzi, who is a lowly 109th in the rankings, who clinched glory at the Telenor Arena in the Norwegian capital.

Riding chestnut mare Fair Light van T Heike, he triumphed after a jump-off which featured 20 horse and rider combinations.

All 20 had gone clear on the course and Zorzi did so again during the extra round, while also producing the quickest time of 36.93 seconds.

He was the first to go in the opening round and then again in the jump-off, with nobody able to match his speed.

"This was a dream," said Zorzi afterwards.

The Italian is the early leader in the overall standings with the second leg of the tour taking place in Helsinki next weekend.

Today's runner-up was three-time World Cup title-holder Marcus Ehning, riding Funky Fred for Germany, who went clear in the jump-off in a time of 37.94.

Belgium’s Pieter Devos was third with Dream of India Greenfield, clocking 38.10 after another clear round in the jump-off.