In a 12-horse jump-off at Telenor Arena, the 22-year-old threw down a brilliant round when third to go and, despite their best efforts, the rest of the world-class field could not catch him.

He clocked a time of exactly 40.00sec to beat nearest challenger Luciana Diniz of Portugal, riding Vertigo du Desert, by 0.40 seconds

Home favourite Geir Gulliksen and VDL Groep Quatro finished third in 40.99.

Balsiger, making only his second-ever FEI Jumping World Cup start, was not the obvious winner on the start-list for the opener of the 14-leg Western European League, from which nine riders will qualify for the 2020 final in Las Vegas in April.

He was full of praise for the 11-year-old horse he has been competing on now for more than three years.

"He gives me 200 per cent at every show and together we have won gold at the Young Rider Europeans and at the Swiss Championships," Balsiger said.

"But this is the biggest win of our career.

"He's so brave, and he gives his heart for me every time."

This is how you doooo it! ?

At just 22, Bryan Balsiger has won his very first @LonginesEq FEI Jumping World Cup class in rockstar fashion! The definition of team work, Bryan and Clouzot de Lassus made light work of the tight track and even tighter time - looking as cool as ice! pic.twitter.com/4Wc6e8BAvD

— The FEI (@FEI_Global) October 20, 2019

The time allowed of 78.00 proved difficult to get in the first round over the course designed by Italy's Elio Travagliati, so there was a huge cheer from the home crowd when Gulliksen squeezed through in 77.98 to make the cut into the jump off with the nippy little VDL Groep Quatro.

Balsiger and Clouzot de Lassus set the target at 40.00 when third to go in the second-round race against the clock.

Gulliksen looked set to challenge that with a great run from VDL Groep Quatro when next into the ring, but the clock stopped on 40.99, and when Diniz steered her 10-year-old gelding, Vertigo du Desert, through the timers in 40.40, the Norwegian slipped down to third.

Brazil's Marlon Módolo Zanotelli, the individual and team gold medallist at this year's Pan American Games in Lima, set off at a scorching pace but, hampered by a stumble after the third fence, hit the first element of the following double and ultimately cleared the line in 40.26.

Then French rider Olivier Robert, who had already made a miraculous recovery when he jumped out of the saddle over the penultimate oxer in the first round, experienced almost exactly the same result over the same fence second time out to come home clear, but in a time of 42.64 with Tempo de Paban.

The leading time appeared beatable and, third-last into the ring, Sweden's Peder Fredricson and H&M All In proved it was when breaking the beam in 38.47.

But the Rio 2016 Olympic silver and 2017 European gold medal-winning partnership left the first element of the double on the floor, so when Germany’s Christian Kukuk and Colestus had a stop at the third, there was only one man left to challenge Balsiger.

That was fellow Swiss and world number one Steve Guerdat, partnering the horse with which he won his third FEI Jumping World Cup title in Swedish city Gothenburg in April.

Setting off at a lightning pace, Guerdat and his horse Alamo looked seriously threatening until finding themselves on a wrong stride to the vertical before the double.