The clock is ticking on American Lindsey Vonn's bid to defend her Olympic downhill title as the injured US star officially withdrew Friday from next week's World Cup stop in Beaver Creek. Vonn was due to return to racing at Beaver Creek for the first time since reconstructive surgery of her right knee in the wake of a crash at the world championships in Schladming, Austria, in February. But she crashed on a training run at Colorado's Copper Mountain on Tuesday, and suffered a partial tear of one of her reconstructed knee ligaments. "Lindsey is extremely appreciative of the outpouring of support and good wishes," her spokesman Lewis Kay said Friday. "While her rehab is progressing, she is not at a point where she will be able to ski next week and is unfortunately withdrawing from the race at Beaver Creek. "She will continue to do therapy with an eye at racing in Lake Louise." After a downhill, super-G and giant slalom at Beaver Creek November 29-December 1, women's alpine World Cup racers are slated to contest two downhills at Lake Louise, Canada, on December 6 and 7, and a giant slalom on December 8. Orthopaedic surgeon Bill Sterett of Vail, Colorado, who operated on Vonn in February, is overseeing her rehab. "Lindsey is recovering very quickly from abrasions to her face and contusions to her shoulder blade," he said in comments released through Kay. "Beyond that, she has a stable knee with an MRI finding of a partial tear of her ACL graft. With therapy, she is progressing well while not losing any of the strength she worked so hard to achieve." Vonn, also a four-time overall World Cup champion and two-time world champion, resumed skiing in August. She skipped the giant slalom season opener in Austria for more time to train, saying her main focus this season is the Sochi Olympics that start on February 7. The 29-year-old is hoping to emulate the feat of former US speed queen Picabo Street, who came back the season after reconstructive surgery to win an Olympic gold medal at the 1998 Nagano Games. Source: AFP