updated 7:52 p.m. ET March 6, 2009

OFTERSCHWANG, Germany - Lindsey Vonn edged closer to making American skiing history — and her coach said she could do better.

The defending overall champion finished eighth in a giant slalom won by Kathrin Zettel on Friday and is poised to become the first American woman to capture two overall titles, much less in consecutive years.

“It’s great Lindsey has such a big lead in the overall, but she wasn’t happy with the way she skied today,” U.S. Ski Team coach Jim Tracy said. “She skis to be on the podium in every race and she’s at a level where she can do that, she expects more of herself.”

Her nearest overall rival, Maria Riesch of Germany, was 22nd in the GS. Vonn has a 414-point lead in the overall standings with five races left and will clinch the title if she leads Riesch by 401 points or more after Saturday’s slalom.

Vonn, a speed specialist who won her second straight downhill title last weekend, has her work cut out. Riesch is the slalom world champion and leads the World Cup slalom standings, having won four races to two victories for Vonn in the discipline.

Phil Mahre and Bode Miller are the only Americans to have multiple World Cup overall titles, with Miller winning two and Mahre taking three straight beginning in 1981.

Zettel remained the World Cup leader in the giant slalom with her fourth victory in the discipline this season. Teammate Elisabeth Goergl trailed by 0.12 seconds. Zettel increased her lead over Tanja Poutiainen of Finland, who finished third.

Slideshow   Women to watch Check out these top competitors in the women's alpine skiing circuit, including American Lindsey Vonn. NBC Sports

Zettel, second after the first run, won in a combined time of 2 minutes, 36.48 seconds. Goergl moved up from fourth and Poutiainen gained two places.

Zettel leads Poutiainen by 41 points with one giant slalom race left in the season.

“It was a very important victory, it increased my lead,” said Zettel, who entered the race only one point ahead. “A lot can still happen, though. One mistake, one crash and it could be all over.”

Tina Maze of Slovenia, who led after the first run, dropped to fourth.

Zettel overcame difficult conditions on Ofterschwang’s Horn course, racing both runs with few mistakes in steady snowfall for her sixth career victory.

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