Allyson Felix is aiming for a fourpeat in the 200, but can she outrun Jamaica's Shelly-Ann Fraser-Pryce?
Paul Gilham/Getty Images
Look for the Kenyan men to be stronger. Look for the Ethiopian women to be stronger.
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide—from Peter King, Tom Verducci, Lee Jenkins, Andy Staples, Grant Wahl, and more—delivered straight to you, along with up-to-the-minute news and live scores.