Britain's Olympic 400m hurdles bronze medallist Natasha Danvers again lost out to Beijing champion Melaine Walker at the IAAF Grand Prix in Rieti.
Danvers finished second, 0.24 seconds behind the Jamaican - who continued her superb season by winning in 55.01 secs.
Fellow Briton Harry Aikines-Aryeetey ran a personal best of 10.10s to finish fourth in the 100m final.
Jamaica's Asafa Powell, who clocked 9.77 in his heat, won in 9.82s despite making a poor start.
Fellow Jamaican Michael Frater was second in 9.98s, while France's Ronald Pognon was given third place despite sharing the same time with Aikines-Aryeetey.
Another Briton, Craig Pickering, was seventh in 10.17s.
Running on the same track in Italy where he set the then-world record of 9.74s a year ago, Powell also posted a false start in the final and felt he should have challenged Usain Bolt's current mark of 9.69s.
606: DEBATE
At the same meeting, British number one Martyn Rooney ran 45.52s to finish second in the 400m behind Gary Kikaya, while David Gillick was seventh.
Marlon Devonish clocked 20.63s as he finished sixth in the 200m, which was won by Zimbabwe's Brian Dzingai in 20.34s.
Emma Ania was fifth in the 100m in 11.31s as Jamaica's Olympic champion Shelly-Ann Fraser continued her impressive form with victory in 11.06s.
In the mile, Kent's Lisa Dobriskey finished fourth in four minutes 20.35s after losing out in a fast finish to Ethiopia's Gelete Burja, who snatched the win in 4min 18.23s ahead of world champion Maryam Jamal and Shannon Rowbury of the United States.
Dobriskey's Team GB Olympic team-mate, world junior champion Stephanie Twell, was never in contention, finishing 14th in 4:32.84.
And Helen Clitheroe - the UK's 3,000m steeplechase record holder - finished 10th in 9.59.84 as Ruth Bisibori Nyangau of Kenya won easily in 9:21.30.
Competing in Dubnica, Slovakia, Britain's high jump silver medallist Germaine Mason cleared 2.3m but was beaten into second place by Sweden's Stefan Holm, who managed 2.32m.
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