American Lindsey Vonn reacts to her disappointing performance in the women's super-G event Tuesday at the world alpine ski championships in Garmisch-Partenkirchen, Germany. ((Alain Grosclaude/Getty Images))

Lindsey Vonn is clearly not herself. Perhaps more worrying, the Olympic downhill champion isn't sure when she'll be fully recovered from her head injury.

Attempting to defend her super-G title title in the opening race of the world championships in in Garmisch-Partenkirchen, Germany, Vonn finished seventh Tuesday — a dismal performance given her commanding strength in this event. She was 0.84 seconds behind Austrian winner Elisabeth Goergl.

"It's like I'm skiing in a fog," Vonn said.

She lost time at each checkpoint and became increasingly shaky as she completed her run. On the bottom half of the icy and shady Kandahar course, she was wild and struggled simply to maintain her line. At the finish, Vonn hung her head on her poles.

"I can't process the information fast enough and that's why I'm behind the course, all the bumps are throwing me around," she said. "It's because my body is one gate ahead of where my mind is, and that's not a good way to ski."

Vonn landed on her head during a spectacular fall in giant slalom training in Austria last week and pulled out of Friday's World Cup slalom.

"It's very frustrating because it's not pain. I can't just fight my way down and fight my way through the pain. I have no fight; I can't think," she said. "It's awful, it's awful."

Vonn's status is in sharp contrast to that of U.S. teammate Julia Mancuso, who took the silver medal. She finished a mere 0.05 seconds behind Goergl for her fourth career medal at the worlds, adding to her three Olympic medals. Maria Riesch of Germany won the bronze.

Mancuso also finished second in a downhill in Cortina d'Ampezzo, Italy, a couple weeks ago. Still, she hasn't won a race in nearly four years.

"I'm getting more and more confidence, and I will be looking for those five hundredths the rest of the week," Mancuso said.

Best shot at victory

Vonn had left open the possibility of skipping this race. But she called it her best shot for victory and couldn't hold herself back. After all, in a streak stretching two years, she had reached the podium in her last 19 super-G's, winning 13 of them.

"I tried to trick myself into thinking I would be OK, and I think maybe it was the wrong decision to even try to race today, but I'm too stubborn," she said. "I couldn't give up."

Vonn's husband and chief adviser, Thomas Vonn, a former U.S. Ski Team racer, agreed that the decision to race was not a good one. The problem is, Vonn feels fine when she's not racing. Free skiing on the course Monday also proved no problem.

"She's been medically cleared, but there's a difference to being able to perform at the highest level on the gnarliest hill at 80 mph [128km/h]," Thomas Vonn said. "It's like driving your minivan to the grocery store or driving an F1 car. There's a big difference."

Vonn had a scan on her head after the fall last week, and has consulted with physicians in Zwiesel, the site of last weekend's races, as well as a doctor in Salzburg.

U.S. women's head coach Alex Hoedlmoser said Vonn was being checked daily and given tests where she has to answer questions under elevated heart rates.

The women have downhill training Wednesday and Thursday, with the next race the super-combined Friday. Then comes the downhill Sunday, with Vonn the defending champion.

Vonn will assess her condition day by day.

"My main focus is the downhill at this point," she said. "It's not looking good for the super-combined and I think I'm not going to do some of the training runs."

Given her competitiveness, even that won't be easy.

"I have a really hard time saying no and not racing, but I have to really take the time to figure out what's more important to me: my health or trying to defend titles," she said.

Vonn has a long history of skiing through injuries. She sliced her thumb on a champagne bottle during a victory celebration at the last worlds in Val d'Isere, France, and bruised her shin on the eve of last year's Vancouver Olympics.

This injury is different, though.

"It's unique to us," Thomas Vonn said. "We haven't dealt with something like this before. Normally she's used to being able to say, 'Ouch, my knee hurts, forget my knee and go.' You can't really do that with your brain."