Tyson Gay helped the U.S. men qualify fastest for the final of the men's 4x100-meter relay, only minutes after the American women's team dropped the baton in the heats.
The former 100- and 200-meter world champion was part of the American team that placed second at the london Games but was stripped of the medal because of his doping violation.
The Americans - with Justin Gatlin sitting out the heats - got the baton around in 37.65. Japan won the second heat in an Asian record 37.68 to qualify second fastest, shaving 0.14 off the regional mark China had set in the first heat.
Usain Bolt didn't run in the heats, but his Jamaican teammates qualified by placing second to Japan.