Team GB's lightweight men's rowing four of Richard and Peter Chambers, Chris Bartley and Rob Williams posted a commanding semi-final victory at Eton Dorney, and will go for gold on Thursday.
The women's eight and the men's double scull of Bill Lucas and Sam Townsend progressed to their respective finals, while Alan Campbell moved into the semi-finals of the single sculls.
Sailor Paul Goodison was 16th and second in the Laser races, but the Yorkshireman is struggling with a back injury and when asked if he was worried his regatta was in danger, he said: "Yeah, for sure."
Star defending champions Iain Percy and Andrew Simpson lead the way and sit four points clear of nearest rivals Brazil after winning one of their two races. Olympic debutant Ali Young secured two second-place finishes in the ongoing Laser Radial class, while Stevie Morrison and Ben Rhodes were third and then 18th, after capsizing, in their 49er races.
The women's match racing team secured round-robin victories against Finland and France. In the RS:X windsurfing, Nick Dempsey began with a fifth and seventh, and Bryony Shaw had a seventh and a sixth.
British fencing experienced a grim day as Richard Kruse, Husayn Rosowsky and James Davis bowed out. Rory Warlow and Richard Brickell missed out on places in the final of the men's skeet shooting.
Welsh weightlifter Gareth Evans set three personal bests in the men's 69kg, while there were judo defeats for Euan Burton and Gemma Howell. Archers Naomi Folkard and Alison Williamson bowed out of the individual competitions, and there was canoe slalom disappointment when world number one David Florence failed to reach the final.
Great Britain's men handballers lost 41-19 to Sweden, while Tonia Couch and Sarah Barrow failed to end the long wait for a female Olympic diving medallist, finishing fifth in the platform synchro.
Britain's remaining badminton players Rajiv Ouseph and Susan Egelstaff slumped out on day four at Wembley Arena. The women's hockey team beat South Korea 5-3, with goals from Nic White, Crista Cullen, Alex Danson, Georgie Twigg and Chloe Rogers taking them top of Pool A after two matches.
The basketball men's team were edged out 67-62 by Brazil, while beach volleyballers Shauna Mullin and Zara Dampney lost 21-18, 21-12 to Italian opponents and the indoor volleyball side lost 25-15, 25-18, 25-20 to Australia. The news was no better in water polo where the men's team were trounced 21-7 by Serbia.