Seven of the oarsmen from the defeated Star eight from last season have spread across two fours this year. The coxed four upset fancied Eton Vikings by four lengths in the Britannia Challenge Cup in the morning, and the coxless four beat Nottingham RC "C" by a resounding five lengths in the Wyfold Challenge Cup late in the day.
"We're just a small provincial club that makes the most of what we've got," said their coach, double Olympian Peter Mulkerrins. "We'll focus on getting through to Sunday's final then whoever we look across and see is whoever we look across and see."
Wednesday is often a day when "selected" crews – who are allocated places in the draw on the basis of results this season – progress easily through the draw but Star and Tideway Scullers' School both overturned the odds in the Britannia Challenge Cup.
Scullers provided Oxford's 2011 Boat Race winner Ben Ellison with his first victory in a race at Henley, as they rowed through Phoenix RC of South Australia to win by 1.5 lengths.
"I've never won a race at Henley and when the Aussie crew led us at the half mile, I thought I'd have to wait a little longer," said Ellison. "Crossing the line was a great feeling."
Another selected crew, the Americans from Belmont High School, came through a nail-biting race in the Princess Elizabeth Challenge Cup for school eights. They beat their local rivals Boston College HS by half a length, having trailed at the three-quarter mile mark.
"We've been scrimmaging with them back on the Charles so we knew they were strong guys and good racers," said Belmont coach Chris Richards. "They pressed out early and took advantage but the stream evens out in the middle of the course and our game plan was to come through there."
The Regatta began in hectic fashion as club-mate beat club mate in the first race of the day and there was a disqualification in the third.
East London club Curlew's first eight was pitted against their B crew first thing on Wednesday morning in the Thames Challenge Cup, and duly won by 4.75 lengths.
"We took a nice composite photo afterwards. It was unfortunate that we raced at 830am and were drawn together but the silver lining is that we'll have a crew there on Thursday," said their coach, Ray Cassidy.
Potomac BC from Washington DC were the first of a record 133 overseas crews at the regatta to see action, in the Wyfold Challenge Cup for coxless fours. However they were disqualified for a clash with London Rowing Club's B crew just a quarter of a mile down the course. Umpire Boris Rankov had already warned the Americans once for poor steering.
Great Britain's team for the London 2012 Paralympics was announced during Wednesday's lunch interval and the four crews - including Tom Aggar, world and Paralympic champion in the arms-and-shoulders single scull – rowed down the Henley course through the enclosures.
"It was a fantastic honour to row in front of such an appreciative crowd at the most prestigious rowing event in the world," said Aggar, who has never been beaten at international level during a five-year career.
"We don't get the opportunities to row on rivers that often so it was a fantastic experience."
On Sunday, two members of Great Britain's eight from the 1948 London Games will take to the water again as a group of Olympians row the royal barge Gloriana over the course at 11am. Michael Lapage and Paul Bircher, who were part of the crew that took silver on the Henley course 64 years ago, will row alongside members of the GB Olympic champion eight from Sydney in 2000.
Six further events get under way on Thursday, including the Diamond Challenge Sculls, where multiple world lightweight champion Duncan Grant and British Under-23 Graeme Thomas – who finished fourth at the recent Munich World Cup regatta – are among the men to watch.
Dan Ritchie, stroke of the British eight that won two world silvers in 2010 and 2011 but missed out on an Olympic place because of injury, is in action in the Silver Goblets and Nickalls' Challenge Cup for pairs, along with fellow GB squad member Tom Broadway.
They could face two multi-talented Americans: former world champion Jamie Koven and world medallist Mike Blomquist - again two men who just failed to make the US eight for the Olympic regatta – in Sunday's final.
Ed Grisedale and Joe Guppy, Great Britain's top junior double, represent Northwich Rowing Club and Eastbourne Rowing Club respectively in the first round of the Double Sculls Challenge Cup, with selected crews gaining a bye to Friday.
Two of the three British women's eights in the Remenham Challenge Cup are in action in a preliminary round for the event, which has been expanded from eight to 10 crews this year. Thames RC and Henley RC take on Radcliffe Crew from Harvard University, while Newcastle University face Germans Munchener RC and Hurther RG.
Fred Gill, Cambridge University's winning Boat Race stroke in 2010, is part of a strong Molesey composite coxless four with Oxford Brookes University in the Visitors' Challenge Cup. Drawn on the Buckinghamshire station, they face a tough challenge from Imperial College and University of London in their opener.