RadioShack rider forced to withdraw from race during fifth stage.

Hours after defending himself against doping allegations by an ex-teammate, Lance Armstrong is going to the hospital for X-rays after crashing during the Tour of California.

Armstrong's longtime coach Johan Bruyneel tweeted Thursday that Armstrong was involved in a "huge" crash and "had to abandon and is going to the hospital for Xrays."

The cyclists were on a two-lane road outside Visalia a few miles into the race when a rider in the main group skidded on some gravel and fell, causing others, including Armstrong, to crash.

Afterwards, Armstrong sat on the ground with his legs spread out, his elbows on his knees and his hands on his face. His left cheek was bloodied in the wreck, and his left eye appeared swollen.