Michael Johnson says the sport doesn't need another Usain Bolt

Four-time Olympic 400m champion Michael Johnson spoke with the media before the start of the finals on Day 3 of the USATF Outdoor Championships. Johnson was the 400m world record holder for 17 years before Wayde Van Niekerk of South Africa ran 43.03 at the Olympic Games in Rio last summer. He comments on Fred Kerley, who would go on to win the U.S. title later in the day, as well as Van Niekerk's potential in the 200m and how Usain Bolt's imminent retirement will affect track and field.