U.S. & World
Max weighed in at 7 lb., 5 oz, and measured 20 inches long, according to the cyclist's Twitter page.
In a later Tweet, Lance wrote, "Kelly our nurse and Dr. Knight. They were amazing!!"
The seven-time Tour de France winner has three previous children with ex-wife Kristin Richards.
As previously reported on Access Hollywood.com, Lance and ex-girlfriend Sheryl Crow's split over the rocker's desire to have kids.
"She wanted marriage, she wanted children; and not that I didn't want that, but I didn't want that at that time because I had just gotten out of a marriage, I'd just had kids [Luke, Grace and Bella]," Lance says in his July-due biography, "Lance." "Yet we're up against her biological clock — that pressure is what cracked it."
Lance and Sheryl broke off their engagement in 2006.
Related Content from AccessHollywood.com:
PLAY IT NOW: Lance Armstrong's Return To Racing
PLAY IT NOW: Is Lance Armstrong Buying The Tour de France?