Hot favourites the United States led the way in qualifying for the world championships mixed 4x400m relay on Saturday, but defending champions the Dominican Republic did not appear on the start line in the morning heats.

With 200m specialist Gabby Thomas held in reserve for Saturday's final, the US team of Ryan Willie, Rosey Effiong, Justin Robinson and Alexis Holmes looked impressive, but did not have it all their own way on a sodden opening morning.

After its early years, when teams experimented somewhat with the order, the event has settled into a man-woman-man-woman routine, removing some of the drama of major shifts of position during the race.

A brilliant second leg by Britain's Laviai Nielsen swept her past the US's Effiong and into the lead but the favourites pulled it back with the impressive Holmes leading them home in 3:10.41.

Yemi Mary John, sporting an eye-catching “one leg legging”, ensured Britain finished second in a national record 3:11.19, with Belgium third for the other automatic qualifying slot.

The Netherlands are probably best equipped to challenge the US for gold and won the second leg with the peerless Femke Bol looking as if she was out for a morning jog as she brought them home in 3:12.12.

France finished strongly for second in a national record 3:12.25 but Olympic champions Poland missed out after a collision at the final changeover left them with too much to do.

The US won the inaugural world championships event in 2019 in a world record 3:09.34 that still stands but were third in Eugene last year, having also only managed bronze on the event's Olympic debut in Tokyo.