USA once again led the pack with a world junior leading time of 38.70 seconds .
USA once again was followed by Japan ( 39.02 ) and Jamaica ( 39.12 ) , which took second and third , respectively .
USA once again led the pack with a world junior leading time of 38.70 seconds and was followed by Japan ( 39.02 ) and Jamaica ( 39.12 ) , which took second and third , respectively .