The USA completed its sweep of the 4x100m relays when the men came home in 38.70 to take gold.
The US team of Jalen Miller, Trayvon Bromell, Kendal Williams and Trentavis Friday included two gold medallists (Williams and Friday) and a silver (Bromell, also the world junior record holder at 100m*).
Their finish time was just 0.04 shy of the world junior record, and the third-best junior performance ever.
Japan held their feet to the fire, however, arriving at the third exchange almost even with the USA. The team of Takuya Kawakami, 100m bronze medallist Yoshihide Kiryu and 200m finalists Yuki Koike and Masaharu Mori delivered a 39.02 effort for silver.
It was Japan’s best-ever performance in the relay after bronzes in 2000, 2004 and 2012.
Jamaica’s quartet of Raheem Robinson, Michael O’Hara, Edward Clarke and Jevaughn Minzie almost overtook Japan on the final leg but wound up third in 39.12. It was Jamaica’s first time in third after winning either silver or gold at every championship since 2002.
Parker Morse for the IAAF
*pending the usual ratification procedures