Who Is Allyson Felix?

Weeks ago, she couldn't walk. Now she's running for gold.

As the focus in Rio moves to track and field, Team USA's Allyson Felix will shift from cheering on her fellow athletes ("The women continue to kill it here in Rio," she said on Twitter. "I'm completely inspired!") to running for gold herself.

Felix won three gold medals in London four years ago, but an injury earlier this year sent her limping into a qualifying race. In the tightest of photo finishes, Felix missed qualifying for her favorite race, the 200-meter dash, by .001 seconds. "My heart aches that I won't be able to defend my title in Rio in the 200m," Felix wrote on Instagram. "It was my dream to go after the double, but I know God's plan is greater than anything I could imagine."

She will compete in the 400 and relays, but the injury hasn't fully healed. "It's coming along," Felix told NBC. "I've made it from not being able to walk to being here. So I'm just going to give it my all, run with a lot of heart, and I'm feeling pretty good."

Advertisers have flocked to Felix, who appears in a number of campaigns, including Nike, Citi and Bounty paper towels ("Allyson Felix is quicker, and so is Bounty"), which features the sprinter using Bounty to clean up after her dog and even shining a gold medal.

She also appears in a P&G "Thank you, Mom" video with her mother, Marlean Felix, who says Allyson "just doesn't have the give-up spirit." The video has more than 4.5 million views in just a month on YouTube.

Name: Allyson Felix

Age: 29

Country of Origin: United States

Occupation: Olympic gold medal sprinter

Twitter: @allysonfelix