Goldie Sayers broke her own national record to beat a top-class javelin field at the London Grand Prix and lift British spirits on a cold, wet afternoon.
On a day when Phillips Idowu's late withdrawal from the triple jump raised more questions about his fitness ahead of the Olympics, reigning champion Christine Ohuruogu produced a season's best to defeat world 400m champion Amantle Montsho.
Sayers threw 66.17 metres in the first round and followed it with two more throws beyond 64m to push reigning Olympic champion Barbora Spotakova into second and world number one Sunette Viljoen into fourth.
USA's Kellie Wells pulled off a huge shock in the 100m hurdles by beating world champion Sally Pearson, while Blessing Okagbare caused another surprise by beating Carmelita Jeter in the 100m.
Idowu has jumped competitively outdoors just three times this year, and not since the Diamond League meeting in Eugene at the very start of June - and even then he pulled out of the competition in the third round amid rumours of a foot injury.
In his absence his main rival for gold in London, world champion Christian Taylor, put on a show with his final round 17.41m the pick in miserable conditions for jumpers.
But Sayers' best series in her career brought a roar from the packed stands at a sodden Crystal Palace, four years after her previous record took her to fourth at the Beijing Olympics.
Sayers, who turns 30 on Monday, said afterwards: "That was what I was after. I know from that that there is more in there. It's that bit more special because I have some of my best friends in the crowd.
"The last time I threw a personal best was in the Olympic final in Beijing. I would absolutely love to do it again in London - everything seems to come right for me in Olympic year."
Ohuruogu's win in a season's best of 50.42 secs, a year after she trailed home last at the same venue, was the perfect tonic as she aims to defend the title she won four years ago in Beijing.
She has endured a troubled few years since then - struggling with a series of injuries, crashing out of last summer's World Championships with a false start - but ran a far better judged race than Montsho in appalling conditions to battle past in the last 10 metres.
"This is my Olympic title to defend," she said, defiantly, afterwards. "It's getting there, so I'm happy with that. I can't really complain about anything - I'm fit and healthy, so I'm really looking forward to the Games."
Wells' victory over Pearson - who had won 31 of her last 32 races coming into this meet - was not only the shock of the weekend but makes their clash at the Olympics next month one of the most exciting of the Games.
The Australian had been considered an outstanding favourite for gold in London and stormed past the waiting media without saying a word after Wells' raw pace saw her take victory by just one one-hundredth of a second in 12.57 secs.
Okagbare's defeat of world champion Jeter overshadowed a surprisingly poor performance from Jamaica's Olympic champion Shelly-Ann Fraser-Pryce, who struggled out of the blocks and gave up to jog across the line last.
There were promising performances from Britons elsewhere, Ross Murray taking the illustrious scalp of former world champion Bernard Lagat as he kicked hard down the home straight to almost catch winner Silas Kiplagat in the Emsley Carr mile.
The 21-year-old Gateshead Harrier has enjoyed a fine season and will go into the Olympics in the form of his life, while Andrew Osagie's third in the 800m behind Adam Krzczot and Job Kinyor confirmed his status as British number one.
Olympic medal hopeful Robbie Grabarz did not quite get the send-off he had hoped for, his 2.22m for second behind Canada's Derek Drouin a full 12cm off his season's best.
But world indoor triple jump champion Yamile Aldama proved her injury problems of earlier this season are behind her, jumping 14.37m in a competition won by Colombia's Caterine Ibarguen with 14.66m.
Britain's Danny Talbot ran a season's best of 20.59secs for fourth in a 200m won in magnificent fashion by France's Christophe Lemaitre in 19.91secs, putting him third in the 2012 world lists behind Yohan Blake and Usain Bolt.
For Tiffany Porter the afternoon ended far less happily, the hurdler leaving the track in tears after failing to progress from her heat amid more injury concerns.
There was disappointment too for Britain's Martyn Rooney who could only manage sixth in the 400m (45.31s), behind world champion Kirani James. Instead it was Nigel Levine who was Britain's top placed finisher in fourth (45.27s).