Quincy Hall became the latest American to electrify Olympic track and field with an out-of-nowhere comeback, sprinting from far behind in the 400 meters to reel in three runners and capture the gold medal. Hall, buried in fourth place as the runners rounded the last bend, outran the runner on his outside, then two more to the inside to cross the line in 43.40 seconds, the fourth-fastest time ever. Britain’s Matthew Hudson-Smith finished second and Muzala Samukonga of Zambia finished third. Hall is the first American since LaShawn Merritt in 2008 to win the one-lap race. His victory came an evening after American Cole Hocker came from behind late to beat the favorites in the men’s 1500.