(CNN) -- Champion cyclist Lance Armstrong will have surgery Wednesday to repair a broken collarbone he suffered in a fall during a comeback race in Spain this week, he said via Twitter.


Lance Armstrong was competing in Spain to regain full race fitness after coming out of retirement.

"At home finally. Whew. Long coupla days. Surgery at 7am tomorrow," he wrote, or tweeted -- as sending short messages on the Web site is known -- Tuesday evening from Austin, Texas, where he lives.

Armstrong chronicled his day in a series of Twitter messages.

"Back in the good ol' U S of A."

"Back in austin. Headed to the doctor's office."

"At the doc's office. I guess it wasn't such a 'clean' fracture after all. Bummer."

"Getting a CT scan now."

Emerging from a hospital with his arm in a sling Monday, Armstrong said he was "miserable."

"I just need to relax a couple of days and then make a plan," he said.

Armstrong, riding for Team Astana, crashed about 10 miles (16 kilometers) from the end of the first stage of the five-day Vuelta Ciclista a Castilla y Leon race. He said he has never before broken a collarbone in his 17 years as professional.

"It's pretty painful," he said. "Just wait and see how it heals."