Quincy Hall came from behind to win the men's 400m final for his very first Olympic gold medal.It's the United States' first gold in the event since LaShawn Merritt in 2008 - it was the second year in a row the USA had swept the podium.It's the first medal for the United States since Merritt earned bronze in 2016.CLICK HERE FOR MORE SPORTS COVERAGE ON FOXNEWS.COMHall finished the race in 43.40 seconds, a personal best - he was 0.37 seconds off world-record time.He was in fourth place as he entered the straightaway, and by the looks of his face, he