Britain's Perri Shakes-Drayton defeated a world-class 400m hurdles field at the London Diamond League with a personal best to emerge as a genuine Olympic medal contender at the perfect time.
On a damp evening, the 23-year-old home-town girl clocked 53.78 seconds, four tenths of a second faster than she has ever run before.
She left European Champion Irina Davydova trailing in second, with Kaliese Spencer third.
The performance puts her equal second in the 2012 world rankings.
World champion Mo Farah gave himself the ideal Olympic send-off with a dominant 5,000m display, although world 400m hurdles champion Dai Greene was once again beaten by Javier Culson, reversing their positions from the 2011 World Championships.
Tyson Gay came through late to take a depleted 100m after Aries Merritt won the 110m hurdles in the absence of the injured former Olympic champion Liu Xiang.
But it was Shakes-Drayton who produced the performance of the night, going hard from the gun, leading into the final bend and pulling away down the home straight with Davydova (54.63), Spencer (55.08) and reigning world champion Melaine Walker nowhere.
With that run Shakes-Drayton moves to second on the all-time UK lists behind former world and Olympic champion Sally Gunnell. Only Russia's Natalya Antyukh has gone faster this year.
She admitted: "I'm over the moon with the time. Today was an opportunity to race against the best girls. I thought to myself 'C'mon girl, pull your socks up.'
"I had to believe in myself. It gives me confidence to know my training is going well."
Farah completed his own Olympic preparations by accelerating away from Australia's Collis Birmingham over the last 250m to take a dominant win in 13 minutes 6.04 secs.
Farah, who has spent the last few weeks at altitude in Font Romeu in the French Pyrenees, covered the last 800m in one minute and 54 seconds. He will run the 5,000m and 10,000m at the Olympics and is peaking beautifully with the biggest races of his life just a fortnight away.
He said: "It wasn't about times tonight - conditions weren't great. It's important now that I keep working and get a good block of training in, but I can't overdo or underdo it now."
Greene has played second fiddle to Puerto Rico's Culson all season and Culson's speed showed again as he came home in 47.78 from Greene in 48.10. Britain's Jack Green - training partner of his near-namesake - ran a personal best of 48.60 in fourth.
Welshman Greene said: "I wanted a bit more. I would have loved to win in front of a home crowd.
"But I'll be continuing what I've done over the last few weeks - I've run faster than I did last year already."
Gay lagged behind Jamaica's Ryan Bailey and Nesta Carter at 60m but held his speed better than his rivals to surge through late in 10.03 seconds.
Jamaica's Asafa Powell had earlier pulled out before the heats citing a tight groin, with British trio Dwain Chambers, Mark Lewis-Francis and Simeon Williamson failing to reach the final.
Gay said: "I feel pretty good with the victory. I'm in pretty good shape but I need to get back to the physio and work on my groin area."
Liu Xiang's late withdrawal with an injured back, having qualified in style from the heats, denied the large crowd a much-anticipated 110m hurdles showdown with Merritt and Jason Richardson.
But Merritt's rapid 12.93 - matching his own world-leading time - saw world champion Richardson beaten into second, with Britain's Andy Pozzi pulling up at the third flight after a personal best in his heat.
Merritt said: "I didn't expect to run this fast - I only got off the plane two days ago. But I've switched my start from eight steps to seven steps and it's been a sky rocket of improvement."
Chris Tomlinson produced a season's best of 8.26m in the long jump behind Australia's Mitchell Watt (8.28m) to bring his campaign nicely to the boil, while his compatriot Lawrence Okoye's fourth-round discus of 63.33m was good enough for third behind Gerd Kanter and Virgilijus Alekna.
There were also personal bests in defeat for Britain's Julia Bleasdale and Eilish McColgan in the 5,000m.
But there was a chastening return to action for world 1500m silver medallist Hannah England, who trailed home in 11th in her first race since being spiked in Hengelo earlier this season.
Lisa Dobriskey, a former world medallist herself, also struggled back in seventh as Maryam Yusuf Jamal (4 mins 6.78 secs) led home Jenny Simpson and Anna Pierce, but new British champion Laura Weightman impressed in fourth with 4:08.19.