Zara Phillips produced a command performance on her Olympics cross-country debut at Greenwich Park as Great Britain's eventers kept their gold medal dream alive.
The former world champion Phillips, The Queen's granddaughter, was roared to the rafters by a 50,000 crowd that included the Duke and Duchess of Cambridge, Prince Harry and the Duchess of Cornwall.
A day of high drama saw the competition delayed five times because of falls - Sue Benson's 28-obstacle course claimed 15 casualties - and it finished an hour later than scheduled.
And while there were no serious injuries to horses or riders, a slippery surface in places made life treacherous for many combinations.
Britain have won 17 post-war Olympic eventing medals, and they hold silver medal position overnight in the team competition behind reigning European champions Germany ahead of Tuesday morning's showjumping finale.
The Germans are on a score of 124.70, 5.5 penalties ahead of Britain, with Sweden third. The individual competition, meanwhile, has joint leaders in Germany's Ingrid Klimke and Swedish rider Sara Algotsson Ostholt.
Mark Todd, the 56-year-old New Zealander chasing a third Olympic title 24 years after his last one, is third, just ahead of world champion Michael Jung. The top four medal contenders are separated by only 1.3 penalties.
Tina Cook, a double Olympic bronze medallist, is best of the British riders in fifth, 51-year-old Mary King lies sixth, Phillips is equal 10th, Nicola Wilson 20th and William Fox-Pitt 22nd.
The British riders produced an eventing masterclass.
Phillips, Wilson and Cook were among just nine combinations that went clear inside the time allowed of 10 minutes, three seconds, while King collected only 1.2 time faults and Fox-Pitt 9.2.
Phillips said the crowd had buoyed her along on a day that could hardly have gone better for Britain.
The last time Britain won an Olympic team gold was in Munich 40 years, when Captain Mark Phillips - Zara's father - was in the team.
Phillips, who was celebrating the first anniversary of her wedding to former England rugby star Mike Tindall, said: "The crowd was amazing all the way along.
"All these people being here is just incredible. It really makes you want to do better, to go faster.
"I am so pleased, It was hard work, but a great feeling. The crowd was unbelievable, and the best thing is that it is my wedding anniversary today.
"My horse (High Kingdom) is such a dude. He lost a front shoe, so he really stepped up today. The course was very suitable for him."
A tearful Cook went to hug her family after completing her round. Her father, the racehorse trainer Josh Gifford, died earlier this year, while her horse Miners Frolic suffered a life-threatening illness last summer.
But Cook kept her emotions together during a brilliant cross-country display that showcased horse and rider at their finest.
"I knew before coming here that this was going to be a tough course. There were no surprises," she said. "There was good grass coverage out there, but it was slippery for the horses.
"I had to go fast round the course, and I don't necessarily like going that fast, but once a year I will do it.
"Zara has been giving me hell. She calls me granny because she likes to embarrass me because of my age, but I am clearly not a granny. I am hoping that they all think I have done well."
Wilson, who was only called into the British team earlier this month when Piggy French's horse DHI Topper W suffered an injury, set the tone for her team aboard Opposition Buzz.
First to go among the British quintet, the world and European team gold medal-winning combination did not put a foot wrong.
"This really is a dream come true," Wilson said. "It was just phenomenal. The atmosphere was electric. The crowd was so loud that I couldn't hear my minute markers bleeping on my watch.
"He stayed very focused - he is a very experienced horse now. Neither he nor I have seen crowds as big as this, or as loud as this before, but he coped really well. What a fantastic horse.
"This is his favourite stage by far. When he gets to go on cross-country day it's like all his birthdays and Christmases have come at once. He never fails to give me the wow factor."