Title favourite Chandra Sturrup recorded the fastest time in the first round of the women's 100 metres at the world championships on Saturday.
Sturrup of the Bahamas, the fastest woman this year, comfortably won the first heat in 11.08 seconds.
Gold medal rival Kelli White won the third heat in 11.26 seconds followed by a fast-finishing Merlene Ottey, who was given the same time.
Jamaican-born Ottey, 43, who competes for Slovenia, is the most decorated athlete in the history of the championships with 14 medals, including three golds.
"It felt good but the start gun was really quiet and it was tough to hear it," U.S champion White said.
Other heat winners included defending world champion Zhanna Block of Ukraine, in 11.13, Greece's Olympic silver medallist Ekaterini Thanou (11.09) and home favourite Christine Arron who edged out American Gail Devers in 11.15.
The first three in each heat qualified for the quarter-finals later on Saturday along with the eight fastest losers, who included Commonwealth Games champion Debbie Ferguson of the Bahamas.
Lima Azimi made history by becoming the first Afghan woman to compete at the world championships.
Running in long tracksuit trousers, Azimi had to be shown how to start out of the blocks by officials before heat three.
She finished last to a big cheer in a personal best of 18.37.
"It was her first time in the blocks. That was amazing for me to see," White said.