The 41-year-old plans to race on Sunday despite rupturing her anterior cruciate ligament in a World Cup downhill crash in Switzerland last week - an injury that would have sidelined most athletes and has added more lustre to her already indomitable reputation.
Wearing bib number 10, the 2010 downhill champion and World Cup leader in the discipline had to wait for low cloud to lift before she could test her braced left knee at any speed.
Slovenian first starter Ilka Stuhec had crashed earlier, with the Olimpia delle Tofane piste requiring re-grooming, and the session was then halted again as fog rolled in after the fourth skier, Austria's Nina Ortlieb.
Norway's Marte Monsen, who also crashed in Crans-Montana last week, did not start.
Vonn kept warm in her ski jacket while she and her teammates whiled away the time at the top of the mountain by taking selfies and working on their social media or carrying out exercise stretches. They even performed some impromptu dance routines.
When Vonn did get going, more than 90 minutes after Stuhec had started, her run was over in one minute 40.33 seconds and a point proved.
She overcooked one turn and lost speed on the lower slopes but skiers often ease off in training, focusing on lines and terrain.
"Nothing makes me happier! No one would have believed I would be here...but I made it!," she had posted on Instagram as she made her way up the mountain in the morning.
"I'm here, I'm smiling and no matter what, I know how lucky I am. I'm not going to waste this chance. Let's go get it!!"
Ortlieb hailed the "idol and legend".
"I've heard that her knee feels pretty good. She has no swelling in it, and I think she's mentally one of the toughest, so I think she can do it," the Austrian told reporters at the finish area.