The United States set the world record in the 4x100 freestyle mixed relay, clocking 3 minutes, 18.48 seconds in the swim world championships.

Ledecky, trailing McIntosh at the 700-meter mark, surged ahead on the final lap, fending off a hard-charging Pallister as McIntosh faded in the closing meters. With the win, Ledecky remained undefeated in the 800-meter freestyle finals event on the world stage dating back to 2012.