USA smashed the world record in the women's distance medley with a time of 10:36.50 on the first day of the IAAF/BTC World Relays, Bahamas 2015.
The team of Treniere Moser (1200m), Sanya Richards-Ross (400m), Ajee Wilson (800m) and Shannon Rowbury (1600m) took more than six seconds off the previous mark of 10:42.57 that was set indoors earlier this year by a different US team.
They were a few seconds off world record pace after the first split, but a sub-50-second clocking from Richards-Ross put them back on course.
Wilson and Rowbury then increased their lead, which was already substantial, to bring the baton home in 10:36.50.
In second, Kenya set an African record of 10:43.35 while Poland broke the European record with 10:45.32 in third place.