Britain's Iain Percy and Andrew Simpson are guaranteed to end London 2012 on the podium and head into Sunday's medal race well placed to retain their Star class gold.
The Olympic champions of four years ago have an eight-point lead over second-place Robert Scheidt and Bruno Prada after the 10 opening series races. The Brazilian pair did, though, win the first race of the day as Simpson and Percy finished fourth, although the Brits responded superbly to get a bullet.
Ben Ainslie is not quite certain of a podium finish, but heads into his medal race with a fourth Olympic gold in his own hands as only two points separate him and leader Jonas Hogh-Christensen. Elsewhere, Hannah Mills and Saskia Clark lead the women's 470 class after the opening day.
Luke Patience and Stuart Bithell maintain their lead of the men's 470 fleet with a fourth and second, while Ali Young sits fifth in the overall Laser Radial standings after a sixth and eighth. Great Britain's reigning Laser gold medallist Paul Goodison endured a tough day, with an 18th and 12th leaving him eighth overall.
Great Britain's Stevie Morrison and Ben Rhodes sit fourth in the standings after posting a 17th, fourth and 20th. The latter is discarded as it is their worst of the regatta so far.
Great Britain midfielder Ashley Jackson inspired his side to a comfortable 4-1 victory over Pakistan with a performance befitting his stature as one of the world's top players. The 24-year-old was at the heart of almost everything, contributing two second-half goals, with James Tindall and Jonty Clarke also on target.
Becky Gallantree and Hannah Starling scraped through to the semi-final of the women's Olympic three-metre springboard competition at the Aquatics Centre. Gallantree failed to get past the preliminary round in Beijing four years ago but a score of 299.25 was enough to see her finish 16th and just inside the 18-diver cut. Starling was fractionally behind her fellow Briton.
Fred Evans pulled out one of the best final rounds of his career to claim a dramatic revenge victory over Lithuanian puncher Egidijus Kavaliauskas and move within one more win of a guaranteed Olympic welterweight medal.
Great Britain women's handball team's tough introduction to the Olympic Games continued as they slumped to a fourth successive Group A defeat at the hands of Angola, a 31-25 loss ending any faint hopes of progressing to the quarter-finals. Elsewhere, Great Britain's women fell at the first hurdle in the table tennis team event.
The hosts' first window of opportunity to qualify for the quarter-finals of the women's volleyball competition was shut by the Dominican Republic, who beat the Olympic hosts 9-25, 18-25, 19-25. Finally, the women's basketball team suffered a heart-wrenching 80-77 defeat to France in overtime.