Great Britain's Margaret Adeoye set a new personal best to qualify for the 200 metres semi-finals at the Olympic Stadium.
The 27-year-old athlete dipped under 23 seconds for the first time, looking strong to hold off challengers down the home straight and clock 22.94secs in third place.
Abi Oyepitan was even more impressive as she finished second to American Carmelita Jeter in 22.92s in her heat.