Lance Armstrong, in the midst of a much-watched comeback, broke his collarbone Monday in a mass crash during the Vuelta a Castilla y Leon race in Spain and will have surgery.
The injury may jeopardize his participation in the Giro d'Italia, which begins May 9, and hinder his preparations for the Tour de France, which begins July 4.
This was the first time in his career that Armstrong was planning to ride in the world's two most prominent races in the same year.
On Monday, in a Twitter message, the 37-year-old Armstrong said: "Broken clavicle (right) . . . Surgery in a couple of days."
He is expected to fly home this morning.
The seven-time winner of the Tour de France launched his comeback in January with the Tour Down Under in Australia, ending a 3 1/2 -year retirement. The race in Spain was his fourth.
About 30 riders in the main peloton were brought down in the crash in the town of Baltanas. Most got up, but Armstrong remained on the ground until Astana support personnel arrived. He left the race in an ambulance.
In a statement, he said what happened was just bad luck.
"At the end of the race, people started to get a bit excited to win. Everybody wanted to be in the front and a couple of guys crashed in front of me, crossed the wheels and I hit them over the top," Armstrong said. "I have road rash abrasions on the right hip and arm but the big problem is the broken collarbone."
Astana team doctor Pedro Celaya said Armstrong suffered a fracture of the middle third of the right collarbone.
"In 17 years as a pro," Armstrong said, "I've been lucky to avoid one of the most common cycling injuries. The crash has put my upcoming calendar in jeopardy."
Columbia-Highroad team doctor Helge Riepenhof said in a telephone interview that 90% of cyclists who have this injury have surgery to insert a metal plate on the fracture. Riepenhof has been treating Belgian cycling star Kim Kirchen, who fractured his collarbone last month during the Amgen Tour of California.
Kirchen had a plate put in and two weeks later was working on a trainer, Riepenhof said, and was riding on roads within 4 1/2 weeks.
He is scheduled to return to racing March 31.
Via Twitter, Astana team director Johan Bruyneel said Armstrong's fracture was a "clean collarbone fracture." Riepenhof said if that's the case, Armstrong's ability to race in the Tour de France shouldn't be in doubt.
