Julia Mancuso, of the United States, races during the second women's World Cup downhill race at Lake Louise, Alberta, earlier this month. (Jonathan Hayward/AP)

At the end of a lost weekend, Julia Mancuso tossed her skis over one shoulder, her boot bag over another, and began navigating the crowd at the base of a mountain in Beaver Creek, Colo. Her finishes in three World Cup races in three days — 20th in a downhill race, 29th in a super-G, a failure to finish a giant slalom — weren’t befitting of one of American skiing’s brightest stars. Her blank gaze fell down to the snow.

“I definitely feel like it’s tougher once you reach a certain level in your career that when you have ups and downs, you always have to remember that it keeps going,” Mancuso said. “When you’re having breakthroughs when you’re younger, everything seems to work a little easier. It’s always exciting. When you’ve been around a long time, it’s hard when you’re struggling to find the extra bit of energy.”

She is 29, approaching her fourth Olympic Games some 14 years after she made her debut on the relentless World Cup circuit. No American woman has won more Olympic medals in Alpine skiing than Mancuso, who took gold in the giant slalom in 2006 and silver in both the downhill and the combined in 2010. She has developed a reputation as the ultimate big-race skier, because even when she’s struggling, the glare that makes others cower seems to help her perform.

“Everyone knows her for the big events,” fellow U.S. veteran Stacey Cook said.

And yet as she heads to St. Moritz, Switzerland, for a pair of races this weekend, she does so as part of Alpine skiing’s old guard, about which there are many questions. A transition is taking place on the women’s World Cup circuit, and it could be felt in full force in February at the Sochi Olympics.

Mikaela Shiffrin, the 18-year-old American star, is a threat for multiple medals in Russia, even as she is focused on only the slalom and giant slalom. Lara Gut of Switzerland will race in front of her home fans this weekend as the winner of four of seven races — across three disciplines — thus far this season. She is 22, and like Shiffrin has not yet competed in an Olympics.

“I’m not kicking anybody out,” Shiffrin said earlier this month after she placed second in the Beaver Creek giant slalom, the race Mancuso failed to finish. “I like racing with my idols and the girls that I grew up watching. It’s so cool to see them out here still skiing fast. With the younger racers coming up, I’m hoping that they give the veterans a little more inspiration to ski fast again and again.”

That inspiration, though, can be difficult to find, even in an Olympic season. Tina Maze, the 30-year-old Slovenian coming off the World Cup overall championship, has only one top-three finish this season. Lindsey Vonn, the 29-year-old American on the verge of becoming the career leader in World Cup race wins, just eased her way back into competition after a 10-month absence because of a knee injury and will take this week’s races off.

Early in the season, Gut leads the overall standings, which are a combination of results from all of Alpine skiing’s disciplines. A pair of 24-year-olds, Austria’s Anna Fenninger and Tina Weirather of Lichtenstein, aren’t far behind, and another, Germany’s Viktoria Rebensburg, won Olympic gold in the giant slalom in Vancouver.

“I love racing, and of course I love winning,” Gut said after she won both the downhill and super-G in Beaver Creek. “Of course I have confidence now.”

Such an experience can be fleeting. Maria Hoefl-Riesch of Germany won two gold medals at the Vancouver Olympics and was the World Cup overall champion in 2011. At 29, she is experienced enough to be a threat in Sochi — as she showed by winning a pair of downhills last weekend in Lake Louise, Alberta.

But she, too, feels the tugs Mancuso referred to.

“I feel old,” Hoefl-Riesch said, though she smiled. “There are not many girls who are older than me. I’ve been in the World Cup for such a long time, and I’m already talking about the end of my career. It’s maybe this year and maybe another one, I don’t know yet.

“The girls like Mikaela Shiffrin — 17, 18 years old and doing really well — they are young and motivated and full of energy. I am also full of energy, but it’s hard to keep it up over so many years.”

That may be part of what Mancuso is feeling now. In seven races this year, she has finished in the top 20 just once. This after consecutive seasons in which she placed second in the super-G standings. She is old enough that such struggles are familiar, and she has survived them before. Yet it’s still hard.

“When things are going fast, it feels easy,” Mancuso said. “When things are going bad, you feel like you want to give up.”

Two seasons ago, Mancuso came close to doing just that. After races in St. Mortiz — an event in which “she was nowhere,” according to women’s Coach Alex Hoedlmoser — Mancuso contemplated just going home in midseason.

“I told her, ‘I’ve seen you change within one day and be able to race again,’” Hoedlmoser said. “‘Let’s get that mind-set again. Let’s get going in that direction.’”

Mancuso stayed. The next weekend, she won a super-G in Garmisch-Partenkirchen, Germany.

“She can do that again,” Hoedlmoser said. Mancuso says that physically, she feels as strong as she ever has, though she will always have pain in a surgically repaired hip. She knows, too, that she is struggling to get her equipment right, and that factor might trump all others. And in her sport, success and failure are measured by the snap of a finger.

“No matter how tough it is, we’re still getting upset of hundredths of a second — and seconds,” Mancuso said. “I guess it’s hard to put in perspective. If you can measure your happiness by two seconds, it kind of makes you feel stupid if you feel sad.”

When she left the hill at Beaver Creek, she grabbed pens from young fans, signing every autographs. And when one asked for a picture, she crouched down, turned to the camera, and smiled. Her fourth Olympics are two months away. Might that smile come back?