BALTANAS, Spain — Lance Armstrong fractured his collarbone today during a race in Spain, leaving in question his participation in the Tour de France in July.

The seven-time Tour champion said he will fly to the United States and meet with medical experts to decide whether he needs surgery.

"We'll go from there," he said. "I think for the Tour it's a very big problem."

Armstrong was knocked off his bike during a pileup in the first stage of the Vuelta of Castilla and Leon race and was taken to a hospital by ambulance. The American, who crashed about 12.5 miles 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."

Astana team leader Johan Bruyneel said on his Twitter feed that there were no complications in the break, and suggested Armstrong could be back riding soon.

"Clean collarbone fracture," Bruyneel said. "Should be fast recovery."

Armstrong is scheduled to compete in the Giro d'Italia from May 9-May 31. The Tour runs July 4-26.

After falling off his bike, Armstrong sat in the grass beside the road, his right shoulder slumped and his wrist resting on his right thigh. When help arrived, he motioned toward his right shoulder.

Armstrong eventually walked to the ambulance and climbed into the back.

After first being taken to the Rio Carrion hospital in Palencia, Armstrong was taken to the hospital in Valladolid.

The 37-year-old is making a comeback to cycling and is riding with the Astana team as he prepares for another possible shot at a Tour de France title. The Vuelta of Castilla and Leon race was Armstrong's first stage race in Europe since winning the 2005 Tour.

Armstrong started his comeback at the Tour Down Under in Australia in January, where he finished 29th overall, 49 seconds behind winner Allan Davis of Australia. He then finished seventh in the Tour of California in February.

On Saturday, Armstrong raced in the Milan-San Remo cycling classic and finished 125th, 8 minutes, 19 seconds behind winner Mark Cavendish.

The mainly flat first stage of the Castilla and Leon covered 109 miles 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.

Associated Press writer Harold Heckle in Madrid contributed to this report.