Britain successfully defended their Olympic team pursuit crown in a new world record time of 3min 51.659sec at a packed London Velodrome.
Ed Clancy, Geraint Thomas, Steven Burke and Peter Kennaugh broke their own world record to win the Olympic gold medal.
Australia came second in the race while New Zealand earned the bronze medal.
The cycling triumph came on the day that British rower Katherine Grainger captured Olympic gold at her fourth attempt, winning the women's double sculls with Anna Watkins at Eton Dorney.
The duo won by more than a length in 6 minutes, 55.82 seconds. Australia took the silver medal and Poland the bronze.
Grainger sobbed after winning silver in the quadruple sculls at Beijing, the third straight Olympics where she finished runner-up.
But since teaming up with Watkins in 2010, she has not lost a race and the pair set a new Olympic record in the heats.
"It was worth the wait," she told the BBC, adding: "It's just the satisfaction of a job well done."
Watkins said: "I just can't believe it, I just had to ask Katherine if it was a dream."
It was Britain's second gold of the regatta after Helen Glover and Heather Stanning's victory in the women's pair on Wednesday.
Northern Ireland's Alan Campbell followed up Grainger and Watkins' success with a bronze in the single scull.
The men's pair of Will Satch and George Nash also took bronze as Britain's rowing medal haul grew to six.
There was a fourth medal for Britain this afternoon when Karina Bryant beat Iryna Kindzerska in the women's judo +78kg bronze contest.
In the Velodrome, Britain's women's pursuit cycling team broke their own world record during their qualifier.
Dani King, Laura Trott and Joanna Roswell completed their 3000m race in 3:15.669.
Track cyclist Victoria Pendleton, who was disqualified in the team sprint on Thursday for a faulty changeover, returned to action with comfortable wins in the first and scond round of the women's keirin, booking her place in the final.
Ed Clancy, Steven Burke, Geraint Thomas and Peter Kennaugh were also easy winners in their first race in the men's team pursuit.
The quartet are hoping to emulate the men's sprint team who yesterday landed gold in a world record time after controversy in the qualifying.
Meanwhile, Britain's Jessica Ennis has begun her quest for Olympic glory with a stunning result in the 100m hurdles.
She won her race in 12.54 seconds - the fastest time ever recorded for the hurdles in the heptathlon.
It was the perfect start for the 26-year-old in front of a sell-out crowd at the 80,000-seater Olympic Stadium in Stratford, east London.
Ennis, from Sheffield, gave another superb performance in the high jump, clearing 1.86m. It gave her a 25-point lead over her rivals with the shot-put and 200m heats to follow on day one.
"Stepping into the stadium before the hurdles, it just blew me away to be honest," she told the BBC. "The crowd and how they got behind me was amazing.
"I'm literally speechless (about the time). When I crossed the line I had to double-check."
The gruelling seven-discipline event ends with the javelin, long jump, and 800m on Saturday.
Team GB are hoping for a repeat of 'Super Thursday' today after the start of track and field at London 2012.
Britain won three gold and three silvers yesterday in rowing, canoeing, judo, cycling and shooting to lift them to fifth place in the medals table. They are now fourth with 19 medals in total.
In the Aquatics Centre, Rebecca Adlington will look to retain her Olympic title over 800m, after taking bronze in the 400m freestyle earlier this week. The 23-year-old qualified fastest in Thursday's heats.
Also competing today - Andy Murray in the men's singles semi-finals, where he plays world number two Novak Djokovic, and Team GB women's footballers who face Canada in the quarter-finals this evening.
In hockey, the men's GB team have beaten Pakistan 4-1 in their latest match.
One of the main Underground lines serving the Olympic Park was suspended in east London this morning as hundreds of thousands of people made their way to events.
There were no trains running on the Central between Liverpool Street and Leytonstone because of a signal failure in the Bethnal Green area, Transport for London said. The service resumed later.
The breakdown came hours after Prime Minister David Cameron urged people to "come back into the capital" following claims the Games have turned London into a ghost town, with commuters and non-Olympic tourists keeping away from the city.