The re-jigged British boat finished second, half a second behind European champions and Olympic bronze medallist Italy on the course at Sarasota-Bradenton in Florida, with The Netherlands beating a young home quartet to the third qualifying spot in the first semi-final.

Moe Sbihi, the only remaining member of the British crew that took Olympic gold in this class last summer, commented: “The race itself today was job done from our perspective and getting into the final was the most important thing.

“Will was unwell and health is more important than rowing races so the right decision was made at the right time.

“It was never going to be easy for Ollie to come in and sit in a very important seat but he came in and did extremely well.

“He was super relaxed and did a fantastic job helping us get the boat into the final.”

Rio 2016 silver medallists Australia, seeking a first world title in this event for 26 years, won the other semi-final in style ahead of Denmark and Germany.

The fifth day of racing at the Championships took place in flat, calm conditions but produced dramatic action, with all the pressure on crews to take one of the first three qualifying places in their semi-finals.

New Zealand’s replacements in the men’s pair for the unbeatable and now retired combination of Eric Murray and Hamish Bond, Thomas Murray and James Hunter, were beaten in their semi-final by a late burst from Italy’s European champions Matteo Lodo and Giuseppe Vicino. 

The Kiwi pair, who won World Cup III, held second ahead of Serbia’s Milos Vasic and Nenad Bedik.

In the other semi-final, Croatia’s Martin and Valent Sinkovic, staking their claim in a new and relatively open class after winning Olympic gold in the men’s double sculls, were clear winners ahead of Britain’s Tom Jeffery and Thomas George, with France’s Onfroy brothers taking third place.

Jack Beaumont, Jonny Walton, John Collins and Peter Lambert moved through to the final of the men’s quadruple sculls as fastest qualifiers ahead of the Netherlands and Poland, with France’s late charge proving insufficient as they finished a second off the pace.

Olympic medallists Estonia made a swift start in the second semi-final, and although Lithuania eventually overhauled them they held second qualifying spot, with Norway joining them in the final.

Ireland’s defending world champion in the lightweight men’s single sculls, Paul O’Donovan, timed his effort perfectly to win his semi-final, taking over the lead from Switzerland’s European champion Michael Schmid in the third 500 metres, with Brazil’s Uncas Batista taking the third qualifying spot after overtaking the World Cup III winner, Artur Mikolajczewski of Poland.

In the second semi-final, the highly experienced Lukas Babac of Slovakia gave everything and ended up with nothing as he established a halfway lead but then ran out of gas near the end. Norway’s Kristoffer Brun came through to take first place, with New Zealand’s Matthew Dunham second and the fast-finishing Lars Wichert of Germany qualifying in third.

South Africa’s Olympian Kirsten McCann, who has already won a World Cup medal after switching from the double to single in the lightweight women’s sculls this season, was a dominant winner of her semi-final, ahead of Switzerland’s Particia Merz and Marieke Keijser of The Netherlands.

Mexico’s Olympian Kenia Lechuga Alanis took a full boat-length lead with barely 100m of the second semi-final gone, and held it until the 500m point – after which the entire field moved past her. 

Ireland’s Denise Walsh had led the way, and held on to win ahead of Mary Jones of the United States and Sweden’s Emma Freh.

France led the first of the lightweight men’s quadruple sculls semi-finals from start to finish, stroked by the 2015 world champion from the double, Stany Delayre. 

Italy claimed second place ahead of Switzerland, with Germany’s world champions left out of the running.

Greece had recorded the fastest qualifying time in the heats, but they were beaten to first place in the second semi-final by Britain, who edged ahead going into the final 500, with the Greek boat narrowly heading Japan to second place.

France’s unbeaten world and Olympic champions in the lightweight men’s double sculls, Pierre Houin and Jeremie Azou, won with ease ahead of Poland’s Jerzy Kowalski and Milosz Jankowski and Lucas Schaefer and Jason Osbourne of Germany.

Italy won the second semi-final ahead of China, with Belgium third.

New Zealand’s Zoe McBride and Jackie Kiddle were assured winners in the lightweight women’s double sculls, ahead of Poland and Denmark.

The home pairing of Emily Schmieg and Michelle Sechser raised the decibel level with a late charge to reach the final as winners ahead of Romania and the British pairing of London 2012 gold medallist Kat Copeland and Emily Craig.

Britain’s para-rowing mixed coxed four (PR3 Mx4+), already assured a spot in Saturday’s finals, won their morning race for lanes in a World Best Time.

The crew of Oliver Stanhope, Grace Clough, Giedre Rakauskaite, James Fox and cox Anna Corderoy clocked 7min 09.36sec to beat their nearest rivals, the US, by 22 seconds.