Mikaela Shiffrin will leave the Beijing Games without an individual medal after dramatically crashing out of Thursday's alpine combined won by Switzerland's Michelle Gisin.

Gisin, defending her title from the 2018 Pyeongchang Games, was sitting 12th fastest after the downhill, but turned on the afterburners in the slalom to clock a combined winning total of 2min 25.67sec.

It was Switzerland's fifth gold in alpine skiing at the Beijing Games and just the second time anyone had retained their title after Austrian Matthias Mayer did so in the men's super-G.

Gisin's swiss teammate and two-time former world champion Wendy Holdener claimed silver, 1.05sec behind, while Italy's Federica Brignone took bronze at 1.85sec.

Two-time Olympic gold medallist Shiffrin could only look on in frustration after what she said had been a "mindboggling" third failure to finish in China after she previously skied out of both the slalom and giant slalom races.

"I didn't make it to the finish again and that's like 60 percent of my DNF (did not finish) rate from my entire career has happened at this Olympic Games," said Shiffrin.

"I didn't feel pressure there. I mean there's always pressure, but I just felt loose and relaxed. I knew my plan, focused, good skiing and I was doing it and it still didn't work."

Shiffrin lasted longer than the five gates she negotiated in the two technical races before sliding out, but not by much, on a course set by her own coach, Mike Day.

Forcing the edges of her skis, the 26-year-old American went wide on one turn and, as hard as she battled, could not correct her trajectory.

She was left looking back up the "Ice River" course shaking her head in the knowledge that she would not add to golds she had won in the slalom at the 2014 Sochi Olympics and giant slalom four years later in Pyeongchang.

"I had good speed and was moving the right way but I just got too stacked up in this double hairpin," Shiffrin explained.

Shiffrin's exits from her favoured slalom and giant slalom here were the first time since 2011 -- when she was making her World Cup season debut at the age of 16 -- that she had failed to finish in two back-to-back technical races.

Those failures left her questioning her self-belief, but she vowed not to shed any tears because it was a "waste of energy", showing admirable humility and renewed determination to take part in all five individual events as well as Saturday's programme-ending mixed team parallel.

Before the competition started, Shiffrin admitted she would be disappointed to leave the Beijing Olympics without a medal, but also warned it was impossible to have two "perfect weeks" at a Games.