Snowboard cross can be a brutal sport.

Winning gold hinges on insane moments, be they impossible overtakes, a Bradbury-style leg-up thanks to an opponent's crash, or the sheer grit to see a gap and force your way through it.

Yet, just as athletes can ride a cascade of momentum, and their luck, through the rounds towards a medal, sometimes it can all be taken away just as easily.

Australia's Belle Brockhoff looked like she was going to ride a sequence of extraordinary races all the way to the medal podium on Wednesday afternoon at the Genting Snow Park in Zhangjiakou.

Unfortunately, her luck just ran out in the final where she finished fourth.

"Fourth is shithouse," Brockhoff said in typically frank style.

"It's so shit. You're the loser of the big final. You just missed the podium by that much."

It is almost unnecessarily cruel that of all the athletes who make it through to the final, only one walks away empty-handed.

However, even making it to the final, a first for Brockhoff in her third Olympics, was an achievement after what had been a turbulent build-up to the competition.

"A lot of things didn't go my way," Brockhoff said.

"I had a shit couple of days training. I had like a mental breakdown in front of my coach and sport [psychologist] and everything. It wasn't great at all.

Even Wednesday morning's time trials did not go to plan, with Brockhoff finishing 19th after her first run, before eventually qualifying as 18th seed after having a second effort.

"I had my worst time-trial result ever in the sport, so I had to dig deep and put a lot of fight into it," Brockhoff said.

And didn't she fight.

As the weather closed in and a sprinkling of snow began to fall on the competition venue, it seemed like it brought some mischief with it, just a dusting to ignite a competition that almost always results in some sort of carnage.

Brockhoff made it through her round of 32 match-up in control, a straightforward second place barely hinting at the drama to come.

In the quarter-final, however, all hell broke loose.

Brockhoff was last heading into the final few bends, trailing reigning world champion Charlotte Bankes of Great Britain and American Faye Gulini.

But the leading pair tangled slightly on one bend, opening the door for the veteran Australian to fly through and steal a remarkable second place and spot in the semi-final.

"I just saw an opportunity to overtake and I just took it without thinking," she said.

One step closer to glory. Time to start dreaming.

In the semi-final, the luck was again on Brockhoff's side as she somehow skipped through the wreckage of Julia Pereira de Sousa's crash, thinking for all money that she was going down, only to find herself second again and into a final.

Brockhoff's roar of delight as she crossed the finish line gave feeling to the sense that momentum was building in her favour.

Alas, after struggling through the rollers at the top of the course — somewhere Brockhoff said she struggled in all of her runs — she was never able to make up the lost ground, finishing behind Meryeta O'Dine, Chloé Trespeuch and gold medallist Lindsey Jacobellis.

If anyone knows how gold can be won, or lost, in an insane moment, it is Jacobellis.

Back in 2006 — in this same event — Jacobellis attempted a celebratory method grab on the penultimate jump of the course but fell, surrendering a monumental lead to Tanja Frieden, who passed her to win gold.

In the next two Olympics, Jacobellis failed to make the big final, only to then finish fourth at the 2018 PyeongChang Games.

In that time period, Jacobellis had won 10 X Games golds and five world championships, an unparalleled level of dominance.

Now, finally, she has an Olympic gold medal.

"[Redemption] was not in my mind. I wanted to just come here and compete," Jacobellis told the Olympic Media Service.

"[An Olympic gold] would have been a nice, sweet thing, but if I had … thought of redemption, then it's taking away focus on the task at hand, and that's not why I race.

"[2006] really shaped me into the individual that I am, kept me hungry and really helped me keep fighting in the sport."