On day two, Dressel finished fourth in the 50 meter butterfly final with a time of 22.89, missing a medal by 0.05 seconds. On day four, Dressel took part in the 4×100 meter mixed medley relay, swimming the butterfly leg and splitting a 49.92. Along with teammates Matt Grevers, Lilly King, and Simone Manuel, the American team won gold in a new world-record time of 3:38.56. That time broke the record set earlier in the day by Ryan Murphy, Kevin Cordes, Kelsi Worrell, and Mallory Comerford. On day five, Dressel re-set the 100-meter freestyle American record with a 47.17 in the 100 meter freestyle final, en route to winning gold by a margin of 0.70 seconds over silver medalist and teammate Nathan Adrian.