Katherine Grainger and Anna Watkins broke the Olympic record in the women's double sculls, clocking 6:44.33 to win the first heat, and go through to Friday's final.
Melanie Wilson, Beth Rodford, Frances Houghton and Debbie Flood, meanwhile, finished third in the women's quadruple sculls repêchage, and progressed to Thursday's final.
Andy Gregory, Pete Reed, Tom James and Andrew Triggs Hodge won heat two of the men's four, progressing to Thursday's semi-finals. And the men's eight won the repêchage, to reach tomorrow's final.
Men's team of Louis Smith, Daniel Purvis, Kristian Thomas, Max Whitlock and Sam Oldham won bronze in team competition.
In Group B of the women's 58kg weightlifting Zoe Smith lifted 90kg in the snatch at her first attempt before lifting a new British record in the clean and jerk of 121kg.
In the cross-country part of the team eventing, Kristina Cook was the highest-ranking competitor in the individual standings, in fifth, with Mary King one place behind. Zara Phillips was joint 10th, Nicola Wilson 20th and William Fox-Pitt came 22nd.
Heather Watson overcame Silvia Soler Espinosa, of Spain, 6-2 6-2, while Laura Robson also prevailed, defeating Czech Lucie Safarova 7-6, 6-4 to also reach round two.
Tom Daley and Peter Waterfield finished fourth in the men's synchronised 10m platform final.
Sarah Clark went out of the women's -57kg, losing 1-0 against France's Automne Pavia. Daniel Williams was beaten Rasul Boqiev, being knocked out of the men's -73kg in the round of 32.
Paul Drinkhall was eliminated from the singles tournament, defeated 4-0 by German Dimitrij Ovtcharov in the third round.
James Huckle finished in 24th place out of 47 competitors in 10m air rifle and went out of the event with a score of 593 out of 600.
Corinna Lawrence, who had beaten the Chilean Caterin Bravo Aranguiz 15-12 in the first round, lost 15-9 against Romania's Simona Gherman, who is ranked fourth in the world.
Tim Baillie and Etienne Stott are third in the men's canoe slalom, with David Florence and Richard Hounslow in 10th, with both pairs seeking to reach the semi-finals.
Liam Tancock finished fifth in the men's 100m backstroke final. As did world record holder Gemma Spofforth in the women's 100m backstroke final.
Hannah Miley qualified for tonight's 200m individual medley, coming second in her semi-final last night.
Caitlin McClatchey was second in the second semi-final in the women's 200m freestyle to qualify for the final sixth fastest.
Rebecca Turner came sixth in heat three. With the top 16 going through, she came 17th, exiting the event by two hundreths of a second. Sophie Allen was fifth in heat four, 21st overall, dropping her out.
In the men's 200m butterfly, Joe Roebuck and Roberto Pavoni failed to qualify for the semis.
Ben Ainslie finished sixth in race three of the Finn class, falling further off the pace in the overall standings with Denmark's Jonas Hogh Christensen six clear of the three-times gold medallist on four points.
Paul Goodison had a disappointing opening day of the defence of his Laser title, finishing 10th in the first race. Stevie Morrison and Ben Rhodes came 12th in race one of the 49er.
...SO WHO'S GOING TO WIN BRITAIN'S GOLD TODAY?
Today, 10.30am Richard Kruse in individual foil.
Today 3pm Tonia Couch dives in 10m platform synchro.
Today, 4pm Gemma Howell in women's Judo -63 kg.
Today, 8.43pm Hannah Miley in the 200m Individual medley.
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