BALTANAS, Spain — With the road narrowing and cyclists piling up in front of him, Lance Armstrong tumbled hard off his bike. He was left with a broken collarbone that will need surgery and questions about whether he'll be able to contend for an eighth Tour de France title in July. "I'm alive!" he wrote on his Twitter feed. "Broken clavicle (right). Hurts like hell for now. Surgery in a couple of days. Thanks for all the well wishes."
Armstrong will fly back to the United States after being knocked out of the first stage of the Vuelta of Castilla and Leon stage race in Spain.
"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," he said in a statement.
Armstrong is scheduled to compete in the Giro d'Italia from May 9-May 31, then the Tour de France from July 4-26.
"I think for the Giro it's a very big problem," Armstrong said as he left Valladolid University Hospital. "For now, the biggest problem is just the pain."
Armstrong won seven straight Tours from 1999-2005 before retiring. He returned after 3 1/2 years, and at 37 was hoping for another triumphant ride through Paris.
Astana team leader Johan Bruyneel said on his Twitter feed there were no complications in the break, and suggested Armstrong could be riding soon.
"Clean collarbone fracture," Bruyneel said. "Should be fast recovery."
Added Astana spokesman Philippe Maertens: "We are confident he can still race the Tour de France, of course. He will be off the bike, but he can still do condition training."
Armstrong was tossed off his bike during a pileup 12 1/2 miles from the stage's finish Monday. The Texan was grimacing and trying to hold his right arm as he entered an ambulance.
"I've never had this happen before; it's pretty painful," he said. "I feel really miserable."
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.
Astana teammate Levi Leipheimer described the pileup on his Twitter feed.
"Lance was involved in a huge crash as the road narrowed and became very rough," Leipheimer wrote. "He wasn't far from the front, as he was riding top 10 all day."
Armstrong said the crash was no one's fault.
"Toward the end of the race people started getting excited, a bit of wind, some hills and everybody wanting to be at the front," he said. "A couple of guys crashed in front of me, I crossed my wheel, then I hit them and over the top."
Armstrong was first taken to Rio Carrion hospital in Palencia, then to the hospital in Valladolid. In his statement, Armstrong said he had "been lucky to avoid one of the most common cycling injuries" in his 17-year career.
"It has been a pity to lose Lance because we see him with desire of doing a good preparation in this race," said Alberto Contador, Armstrong's teammate and biggest rival for the role of team leader. "Now only I can support him and wish him to recover as soon as possible in order to take the start on the Giro."
This 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.