World champion Dai Greene found himself overshadowed by British team-mate Perri Shakes-Drayton in the athletics Aviva London Grand Prix at Crystal Palace.
Greene had been hoping to break Kriss Akabusi's 20-year-old British record of 47.82 seconds in the 400 metres hurdles, but could only finish second behind Puerto Rico's Javier Culson in 48.10secs.
And it was left to Shakes-Drayton to provide a home victory for the large crowd to cheer in the women's event, with the Londoner storming to a surprise win in 53.77 seconds in a world-class field.
Former Olympic champion Sally Gunnell is the only British athlete to have run faster and Shakes-Drayton's time was also joint second fastest in the world this year, taking 0.41s off her personal best set when winning European bronze in Barcelona two years ago.
The 23-year-old, who had been ranked just 21st in the world in 2012 before the race, said: "I'm over the moon with the time. I thought it was an opportunity to race the best girls which I haven't had this year.
"I thought 'Come on girl, pull your socks up, you have to go for it', and I sure went for it. I just believed in myself and reminded myself what I've done. I've had a good day at the office.
"It gives me confidence knowing that my training is going well but I'm not going to let it get to me too much. I'm still going to remain level-headed because it's not finished yet."
Greene had looked back to his best in Paris last week, clocking a new personal best of 47.84 to miss Akabusi's record by just 0.02s, but he again had to settle for second place behind Culson here.
"I wanted a bit more, I would have loved to get the win before a home crowd," the 26-year-old Welshman said. "My top-end speed has been better recently but it needs to improve again and hopefully I can get it right for the Olympics."
Britain's Jack Green was fourth in the same race, setting a new personal best of 48.60s, while Lawrence Okoye had earlier finished third in the discus with a best of 63.33m.