There are usually casualties in the sprint relay heats at the IAAF World Championships and London 2017 was no different in that regard, with the Bahamas quartet failing to finish the second of two races after a poor second change.
But the likely gold medal contenders, the USA, Great Britain, Germany and Jamaica all progressed in untroubled fashion to set up an intriguing final.
Sprinters aren’t noted for their enjoyment of morning races, but despite the 10:35 am start time, the Olympic champions the USA won the first heat in a world leading 41.84, even in the absence of individual 100m champion Torie Bowie.
Great Britain, too, looked impressive, their 41.93 for second place the third fastest time ever produced by a British quartet, matching their performance in the first heat at the 2016 Olympic Games.
Asha Philip, part of that bronze medal winning team, responded fastest to the gun with a reaction time of 0.118, but the two teams were neck and neck through the first two legs; Philip passing on to Desiree Henry and Aaliyah Brown to Allyson Felix, twice a world sprint relay champion.
It was on the third leg that the USA edged ahead, with Morolake Akinosun running a terrific bend, taking a metre or so from Dina Asher-Smith, fourth in the 200m just a few hours previously.
On anchor, Ariana Washington comfortably held off the fast finishing Daryll Neita, with both teams identifying themselves as likely medallists.
In third, Switzerland set a national record 42.50 to qualify automatically ahead of the Netherlands, for whom 200m champion Dafne Schippers ran a very swift second leg, who also qualified on time.
Felix was optimistic about her chances of adding to her medal collection later in the day. “The aim is gold,” she confirmed. “Hopefully, we have a lot more in the tank. We're ready and we have some great competitors in the back ready to come out here and produce.”
While the first seminfinal saw two dominant teams, the second saw four that were more evenly matched, with less than 0.6 separating Germany, the winners, and Trinidad and Tobago in fourth.
The Germans, fourth at last year’s Olympics, got off to a strong start through Tatjana Pinto, but it was after Lisa Mayer passed on to Gina Luckenkemper that they took a lead that they didn’t give up.
The 20-year-old, who set a personal best 10.95 in the individual 100m, gave Rebekka Haase a narrow lead over Jamaica’s Sashalee Forbes, who took the baton awkwardly from Jura Levy. Haase looked strong, stopping the clock at 42.34 to the Jamaicans’ 42.50.
Just behind were Brazil in 42.77, while a Trinidad and Tobago team of Kelly-Ann Baptiste, Michelle-Lee Ahye, Semoy Hacket and Khalifa St Fort might have expected to finish with a quicker time than 42.91 and a higher placing than fourth, although they still progressed.
Dean Hardman for the IAAF