If the United States women’s eight is to win gold at the Sarasota-Bradenton course it will require an unprecedented effort – they must now restore their confidence in Friday’s repechage as the New Zealanders, whose victory earned them an automatic place in Sunday’s final, enjoy the benefit of four days’ rest.

The blue riband boat class of the Championships had been keenly anticipated by home followers hoping for another golden performance from the latest women’s boat to be coached by Tom Terhaar.

But as a hugely competitive opening heat at the Nathan Benderson Park regatta venue got underway in hot conditions on calm water, it was Rio 2016 silver medallists Britain who took an early lead.

Hopes of a long-awaited change at the top had been sparked at the second of this season’s World Cups as New Zealand and Britain had beaten the relatively young new US team into third place.

New Zealand ended the day with even more tangible encouragement as they overtook Britain and then held off the inevitable US challenge by less than a second.

The Kiwis’ time of 6 minutes 08.42 seconds was the second-quickest of the day, with second heat winners Romania fractionally faster as they headed a powerful Canadian crew and the fast-finishing boat from the Netherlands.

New Zealand have four crew members back from the boat which placed fourth at Rio 2016 – Emma Dyke, Rebecca Scown, Kelsey Bevan and Ruby Tew.

The same foursome were in the eight that won silver at the 2015 World Rowing Championships in France.

What can the US women now muster in response?

Britain, Olympic champions in the men’s eight, will also require an extra race to qualify for Sunday’s final after narrowly failing to catch an Italian crew that had established a clear lead by the first 500 metres mark.

In the end the British crew had to work hard to hold off the fast-finishing Australian crew who eventually had to settle for third place.

Germany, Olympic champions in 2012 but beaten to gold at Rio 2016, arrived in the US ready to re-establish their dominance in this event, having set a World Best Time earlier this season.

Their performance in the second heat did nothing to diminish this effect, as they claimed the other automatic final place in holding off a fierce challenge from a hugely promising US eight that had not raced internationally all season.

The historic distinction of being the first para-rower to win a race over the 2000m distance at a World Championship fell to Norway's sometime cross country skier Birgit Skarstein, who thus qualified for the final of the Para PR1 women’s single sculls, along with second-placed Moran Samuel of Israel.

Germany’s experienced Sylvia Pille-Steppart won the other heat, with US newcomer Hallie Smith excelling to take the second automatic qualifying place ahead of Paralympic silver medallist Lilli Wang of China.

Paralympic champion in the Para PR1 men’s single sculls, Roman Polianskyi of Ukraine, won the first of three heats from Brazil’s Rene Pereira.

The second heat went to Russia’s Alexey Chuvashev, with Britain’s new single sculler Andrew Houghton – who has taken over the boat from retired former Paralympic gold and silver medallist Tom Aggar – securing the second qualifying place ahead of home athlete Blake Haxton.

Australia’s three-times world champion and Rio 2016 silver medallist Erik Horrie underlined the continuing power of his ambition as he won the third heat without seeming effort in the fastest time of the day, with Jaroslaw Kailing of Poland joining him in the final.