Defending champions Canada, however, failed to make it through from their semifinal on Friday.
In the women’s event, another showdown between the US and Jamaica, who have shared the last nine world titles, looks likely after both stormed through as heat winners.
Given their extraordinary depth and quality, the US men have a woeful recent record in the event.
They have not won an Olympic final since 2000 and have just one gold from the last seven World Championships amid a series of fumbles and disqualifications.
On Friday, they lined up Christian Coleman, Fred Kerley, Brandon Carnes, and JT Smith – with individual champion Noah Lyles, one of three Americans going in the 200m final later on Friday – set to slot in for Saturday’s final.
They had a scare with the last handover but Smith clutched the baton at the third attempt and just held off fast-finishing Jamaican Rohan Watson to win the heat in an impressive 37.67s.
Jamaica and a slick Japan quartet followed them through.
“We got the big Q for tomorrow so that was the goal,” said Coleman. “We’re not worried about anybody else. If we get the stick around we’ll be hard to beat.”
“Definitely we want to get gold but you should all be on record watch, for sure.”
Olympic champions Italy, with Tokyo individual gold medallist Lamont Marcell Jacobs running a barnstorming second leg, were impressive winners of the second heat in 37.65s.
South Africa finished second, with the UK overhauling Canada on the last leg for the third automatic qualifying spot as the holders failed to make the final.
In the women’s event Briana Williams, Elaine Thompson-Herah, Shashales Forbes, and Shelly-Ann Fraser-Pryce – three of whom won Olympic gold in Tokyo – brought Jamaica home miles clear in the first heat in 41.70s.
The US were similarly impressive in winning the second in 41.59s, with Ivory Coast setting an African record 41.90s and Italy a national record of 42.14s to join them in the final.
Sha’Carrie Richardson of the US and Jamaican Shericka Jackson, first and second in the individual 100m, should both come into their teams for Saturday’s final after they went head-to-head again in the 200 final on Friday.