ROME, Oct. 23 (Xinhua) -- Lance Armstrong announced via Twitter on Friday that he will race next May's Tour of California, meaning the American cycling star is sure to miss Giro d'Italia scheduled in same month.

    "I've decided to ride the Tour of California in 2010," said the seven-time Tour de France champion.

    The Tour of California starts on May 16, while the Giro, the world's second-biggest stage race only next to Tour de France, begins on May 8 in Amsterdam.

    Armstrong finished 12th in this year's Giro, which he rode for the first time as part of his comeback after three-and-a-half years in retirement.

    The Astana team member ended up third in this year's Tour de France.