YANQING, China — Every Olympics delivers its own crushing surprises: the ill-timed injury, a star figure skater’s tumble to the ice, a mental mistake.

On Monday, under bright sunny skies and on one of the most hectic days in Olympic Alpine ski racing history, it was the American star Mikaela Shiffrin’s turn to experience that sort of heartbreak.

Shiffrin’s failure to survive a left turn early in her Beijing debut in the giant slalom, leading to her disqualification from the event, did not have the drama of her sport’s violent crashes. But it was also not unusual on a day when two stars who figured to provide the sizzle on the slopes were nowhere near the podium.

It was expected to be a scripted day for Shiffrin and Aleksander Aamodt Kilde of Norway, gold medal favorites who are the new power couple in the sport. But it became something else entirely on a long day at the Yanqing National Alpine Ski Centre.

It also set up a pressure-packed moment for Shiffrin in Wednesday’s slalom, her signature event, which she has won more often on the World Cup than any other skier in history. For a woman considered the greatest skier ever, a slip on the big stage will be remembered as something all the greats experience. But two in a row here would be something more.

Kilde, Shiffrin’s boyfriend, will not have to wait long for another chance, either. He will compete in the men’s super-G on Tuesday.

The Olympics, of course, produce more disappointed athletes than triumphant ones. On Monday, it was Shiffrin and Kilde’s turn to come up short when no one expected them to fail.

Shiffrin’s failure to survive a left turn in the giant slalom sent her sliding on her hip and off the course five gates into the race — for just the 14th time in 229 Olympic, world championship and World Cup races.

“The day was finished basically before it even started,” she said.

A little more than two hours after Shiffrin’s tumble, Kilde, a speed specialist and the overall World Cup champion in 2020, skied tentatively early in the men’s downhill and never recovered from a few sloppy moments in the steep, twisting middle section of the course.

He finished fifth, a half-second behind Beat Feuz of Switzerland, who had a winning time of 1 minute 42.69 seconds. That was a tenth of a second ahead of the silver medalist, 41-year-old Johan Clarey of France, who had not won a medal in three previous Olympics but is now the oldest Olympic Alpine medalist. Matthias Mayer of Austria won the bronze.

There is no shame in losing to Feuz, the burly downhill champion of the World Cup the past four years, who claimed his first Olympic gold by skiing in a near tuck for much of the race. Even Mayer had credibility in the race: He was the downhill gold medalist at the 2014 Sochi Games.

It was just not what Kilde, the winner of six speed races this season and two downhills last month, had expected.

“I had high expectations for me today,” he said.

The downhill was wedged between the two runs of the women’s giant slalom after organizers postponed it on Sunday because of high winds. The air was calm Monday, allowing for a safe and fair race for skiers who sometimes fly through the air at speeds of nearly 90 miles per hour.

After days of worry about the unfamiliar course — none of the competitors had skied it until last week — racers said the race was easier than most of the downhills they face on the World Cup tour. But it still delivered what it so often does.

Dominik Schwaiger of Germany crashed hard and writhed, clutching his right arm, when he finally came to a stop. The Austrian Daniel Hemetsberger’s face was bloodied after he hit a gate at high speed. And nearly every skier came within inches of the orange safety netting on a tight left turn near the top of the course.

Kilde said that he knew he was in trouble midway through the race, and that he was not going to have much opportunity to make up the time he had lost. “It’s not a good feeling,” he said. “All you can do is just hang in there.”

Shiffrin never got that chance in the giant slalom on a course that racers said was fast and unforgiving, providing no chance to recover from anything but perfectly linked turns.

Shiffrin, 26, the winner of two Olympic gold medals and the defending champion in the giant slalom, had just entered the steep, icy pitch beyond the start when she lost her balance on a right turn. She then lost control of her skis and battled to get around the next gate in time. When she could not, her left hip hit the snow, and soon she was skidding to a stop.

She was one of a half-dozen top skiers who did not complete the first run. A half-dozen more crashed in the afternoon, including the American Nina O’Brien, who tumbled violently only 20 yards from the finish and was carried off on a stretcher. She was said to be alert and responsive, with no spinal injuries after the violent crash, but she did sustain what appeared to be a serious leg injury.

Of her own fall, Shiffrin said she had perhaps gone too hard too soon, in the belief that the steeper course required an all-out sprint.

“I was trying to push it, but sometimes that is just anxious and it doesn’t work,” she said.

Despite what she called a “huge disappointment” that she will never get over, Shiffrin talked about having had the right mentality, of being proud of the five turns she had completed and of being sorry that she had not been able to ski more on a fun hill in good conditions. She gave her teammate O’Brien technical advice for her afternoon run.

Sara Hector of Sweden, the World Cup leader in giant slalom, won the gold medal with a time of 1:55.69 for two runs, just over a quarter of a second better than Federica Brignone of Italy. Lara Gut-Behrami of Switzerland took the bronze.

Shiffrin later headed back onto the hill to train for Wednesday’s slalom race. She may compete in three other races as well: the downhill; the super-G; and the combined, which has both a run of downhill and another of slalom, and gives her a chance to show off her versatility.

“I’m not going to cry about this,” she said, “because that is just wasted energy.”