Kelsi Worrell Dahlia helped Team USA to set a world record and won gold in the final event of the FINA World Championships in Gwangju, Korea.

The United States led the 4x100M medley relay from wire-to-wire. Seventeen year old American Regan Smith gave Team USA the lead with a split of 57.57. The USA's Lilly King, world champion in the 100 breast, held the lead for the Americans posting the best breast split of the field with a time of 1:04.81. Kelsi Worrell Dahlia handed over the lead to the anchor after her butterfly leg split of 56.16 fly. The anchor, 100M free champion Simone Manuel posted a split of 51.86, to board a new World Record for the USA of 3:50.40, besting the old record by more than a second.

There were actually two World Records set in that race as Regan Smith's split of 57.57 set a new world mark and made her the first woman to go under 58 seconds in that distance.

Australia and Canada dueled down the stretch in the battle for silver with the Aussie's just out-touching Canada 3:53.42 to 3:53.58. The bronze medal time marked a new Canadian Record.