Lindsey Vonn will miss the Sochi Olympics because of a right knee injury, leaving the Winter Games without one of its biggest stars.

The 29-year-old from Vail, Colo., announced her decision today, exactly one month before the opening ceremony in Russia.

Her personal publicist, Lewis Kay, said in a statement that Vonn “will have surgery shortly.”

In a posting on Facebook, Vonn said she is “devastated” to miss the Olympics, “but the reality has sunk in that my knee is just too unstable to compete at this level.”

She took home two medals from the 2010 Vancouver Games, including becoming the first American woman to win an Olympic gold in the downhill. Vonn is also a four-time overall World Cup champion, the most recognized name in Alpine skiing — and, as it happens, the girlfriend of Tiger Woods. 

Add it all up, and she would have been the focus of plenty of media coverage in Sochi, and certainly a main character in NBC’s coverage for a U.S. audience.  

But Vonn tore two ligaments in her right knee during a high-speed crash at the world championships last February, sidelining her for about 10 months. She re-tore her surgically repaired ACL in a training crash in November, a key setback. Then, after returning to competition in early December by finishing 40th, 11th and fifth in a set of World Cup races at Lake Louise, Alberta, Vonn sprained her MCL during a race at Val d’Isere, France, last month.

“I did everything I possibly could to somehow get strong enough to overcome having no ACL,” Vonn said today via Facebook.

“I’m having surgery soon so that I can be ready for the World Championships at home in Vail next February,” she wrote. “On a positive note, this means there will be an additional spot so that one of my teammates can go for gold. Thank you all so much for all of the love and support. I will be cheering for all of the Olympians and especially team USA!”

Mikaela Shiffrin, the reigning world champion in slalom, and Julia Mancuso, a three-time Olympic medalist, will now be the American women with the best chance of stepping on the Alpine skiing podium in Sochi.

Shiffrin, the U.S. teenager who has been labeled the “next Vonn” by some, wrote on Twitter: “It’s hard to swallow that @lindseyvonn won’t be competing in Sochi, but I’m incredibly impressed at her determination. She’s a true #hero.”

Another American ski racer, Stacey Cook, posted on Facebook: “Bummed Lindsey Vonn. Our team is not the same without you. You leave big shoes to fill for the rest of the year.”

After skiing in two downhills and a super-G at Lake Louise, Vonn sounded optimistic, declaring she would be in Sochi, “fighting for my medal.”

But a couple of weeks later in France, during a downhill — with Woods watching in the finish area — Vonn lost her balance, sending her left ski into the air, and forcing all her weight onto her right knee. She grimaced as she pulled up, then clutched that right knee.

Kay said today that an MRI after that episode “showed an MCL sprain, which coupled with the torn ACL, has made it impossible to stabilize her knee and be ready to safely ski again next month.”