RIO DE JANEIRO -- A decade ago, when Olympic sprinter Justin Gatlin was banned from his sport for a doping violation, he thought about spending his time playing professional football.
He tried out with the Houston Texans. And then with the Tampa Bay Buccaneers.
Gatlin quickly learned that it takes more than just world-class speed to make it in the NFL.
"It's so tough," he told The Associated Press. "I would say that how track and field is built without a union and it's a dog-eat-dog world, that's how it is to get into football. It's the same thing: a dog-eat-dog world.