Jamaican Elaine Thompson-Herah is on course to complete a sprint double after equalling her personal best to qualify for the women's 200 metres final.
The 100 metres champion clocked 21.66 seconds to lead the qualifiers for the final, with silver medallist Shelly-Ann Fraser-Pryce also safely through.
Thompson-Herah looked impressive in her race but will be challenged in the final by teammate Fraser-Pryce, Marie-Josee Ta Lou of Ivory Coast and impressive Namibian teenagers Christine Mboma and Beatrice Masilingi.
Great Britain's Beth Dobbin finished fifth in the same semi-final as Thompson-Herah, clocking 22.85 seconds.
100 metres bronze medallist, Shericka Jackson failed to make it to the semi-finals, missing out on qualification by four one-thousandths of a second.
The Women's 200 metres final is at 12.50am tomorrow.
Meanwhile, the men's 200 metres heats begin at 2.05pm today, the semifinal is at 11.50 tonight while the final is at 12.50am Thursday.
