On the first day of competition, July 23, Dressel set the American record in the 50 meter butterfly with a time of 22.76, topping the semifinals. Later that evening in the 4×100 meter freestyle relay, Dressel set the American record in the 100 meter freestyle with a time of 47.26 in the leadoff leg. Combined with Townley Haas, Blake Pieroni, and Nathan Adrian, the American team won gold with a time of 3:10.06, earning him his first gold of the Championships.