Armstrong announced via Twitter on Friday that his girlfriend Anna Hansen is expecting his fifth child in October. He's even set up a separate Twitter account under Cincoarmstrong.

The 38-year-old cycling great has hinted at the new arrival since last week. The first Cincoarmstrong tweet was April 20. It said, "I got 2 arms, 2 legs, a nickname, and i'm 2 inches long. See y'all in October."

Armstrong has three children with his ex-wife Kristin. He and Hansen had their first child together, son Max, in June 2009.