Lance Armstrong fractured his collarbone Monday in a crash during the Vuelta of Castilla and Leon race, putting in doubt his comeback to professional cycling. Armstrong said he would fly to the United States and meet with medical experts to decide whether he needs surgery, leaving in question his participation in the Tour de France in July. “We'll go from there,” he said. “I think for the Tour it's a very big problem.” The mainly flat first stage of the Castilla and Leon covered 176 kilometers from Paredes de Nava to Baltanas. It was won by Joaquin Sobrino Martinez of Burgos Monumental in 4 hours, 31 minutes, 53 seconds after a sprint finish. He was followed by David Vitoria of Rock Racing and Jose Joaquin Rojas of Caisse d'Epargne. In a statement released later Monday, the 37-year-old Armstrong said he had “been lucky to avoid one of the most common cycling injuries” in his 17-year career. “The crash has put my upcoming calendar in jeopardy but the most important thing for me right now is to get back home and rest up and begin my rehab,” Armstrong said. Armstrong was knocked off his bike during a pileup in the first stage of the race and was taken to a hospital by ambulance. The American, who crashed about 20 kilometers from the stage's finish, was grimacing and trying to hold his right arm as he entered the ambulance. “The collarbone is broken and I have a little bit of road-rash abrasions,” Armstrong said as he left Valladolid University Hospital. “I've never had this happen before, it's pretty painful. I feel really miserable.” X-rays confirmed that Armstrong fractured his right collarbone. Astana team leader Johan Bruyneel said on his Twitter feed that there were no complications in the break, and suggested that Armstrong could be back riding soon.