Noah Lyles highlights 200m, Allyson Felix in 400m semifinals

A new champion will be crowned in the men's 200m after Usain Bolt won gold in the event at the last three Olympics. Will 24-year-old Noah Lyles take up Bolt's mantle Wednesday morning or will 17-year-old Erriyon Knighton be the one to win gold before he even finishes high school?