The United States have posted the fastest time in the 4x100m freestyle mixed relay in the heats at the World Swimming Championship in Russia.
Conor Dwyer and Ryan Lochte ensured that the Americans made a strong start before Margo Geer and Abbey Weitzeil brought it home in 3:24.51.
The quartet finished 0.72 seconds faster than second-placed Russia, while Italy completed the top three.
Despite winning gold in the women's 4x100m freestyle and individual 100m freestyle, plus silver in the men's 100m freestyle, Australia withdrew from the event.
