Lindsey Vonn has called an early end to her skiing season, dealing a major blow to the American star's hopes of capturing her fifth alpine World Cup overall title.

Vonn said Wednesday the left knee injury she suffered after crashing in a super-G race Saturday in Andorra is more serious than originally thought.

Vonn crashes during Super G event in Andorra6:00

Initial x-rays showed a hairline fracture, and Vonn raced Sunday in a combined event, extending her overall lead by finishing in 13th place.

But she said Wednesday that further tests showed three fractures.

"After the super combined on Sunday, I went to Barcelona where more precise MRI and CT equipment was available and scans were performed on Tuesday morning," Vonn said in a statement on her website. "Those images showed that there was not just one hairline fracture, but in fact three. And the fractures are not hairline, but instead they are significant enough that they are not sufficiently stable to permit me to safely continue skiing."

Vonn called the move to end her season "one of the toughest decisions of my career" but said she didn't want to risk missing future marquee events.

"With the world championships in St. Moritz next year and the Winter Olympics in South Korea the following year, I cannot take that risk," she said.

Vonn last won the World Cup overall title in 2012, when she completed a run that saw her take the crown in four of five years and finish second in the other.

Gut in hot pursuit

Switzerland's Lara Gut is 28 points behind Vonn in the overall standings. She has 1,207 to Vonn's 1,235, while Germany's Viktoria Rebensburg is well back with 914.

The winner of each race gets 100 points, second place gets 80, third gets 60, and point values continue to decrease from there, with the top 30 receiving points. A ninth-place finish, good for 29 points, would vault Gut past Vonn.

Eight races remain on the women's schedule this season. Two of those are slalom events, which Gut does not typically enter.

Vonn won nine races this season after a hampered preparation. She missed the season-opening race in October after a 10-week layoff because of a broken ankle bone, a year after coming back from the injuries that kept her away from the 2014 Sochi Olympics.

In her first World Cup appearance of the season, Vonn swept the events at Alberta's Lake Louise, winning a pair of downhills and a super-G.

In Cortina, Vonn won a downhill to eclipse Annemarie Moser-Proell's mark of 36 career wins in skiing's marquee event. Vonn now has 38.

Vonn also holds the all-time record for women's World Cup wins in all alpine events, with 76. She also owns a pair of world titles and won Olympic downhill gold in 2010 in Vancouver.

Season-ending injuries have now struck World Cup overall leaders on both sides this year. Men's front-runner Aksel Lund Svindal was ruled out for the season with a knee injury from a crash in January in Kitzbuehel, Austria.

With files from The Associated Press