USA on Sunday ran to the top of the pile with a world record time of 3:09.34. Felix was level with Bolt with most gold medals at the Worlds before she helped Michael Cherry power clear on the last leg. Cherry helped the USA surpass Poland and take the lead.
Poland had sent its two men out first in a bid to build an unassailable lead and they were leading comfortably until Cherry’s run. Felix ran the second leg for her team.
Poland ended up without a podium finish, with Jamaica claiming second and Bahrain finishing third.
Felix, 33, now has a dozen golds at the world championships in five different events: 200m, 400m, 4x100m, 4x400m and the mixed 4x400m.