Defending champion and world record-holder Genzebe Dibaba got her World Championships campaign off to a good start.
The Ethiopian clocked the fastest 1500m heat time with 4:02.67, just eight hundredths slower than her heat time from 2015, when her 4:02.59 clocking was the fastest ever heat time recorded at an IAAF World Championships.
However, hot on Dibaba's heels in heat one was South Africa’s Olympic 800m champion Caster Semenya. The 2009 world champion – who has shown top form in 2017 with a 1:55.27 lifetime best at the IAAF Diamond League meeting in Monaco – looked comfortable throughout and came through strongly over the final 100 metres to clock 4:02.84 for second, reiterating that this event looks set to be one of the most competitive of the championships.
Having taken the race out fast from the gun, leading through 400m in 64.53 and 800m in 2:11.44, Great Britain's Jessica Judd was rewarded for her front-running with a 4:03.73 personal best and the sixth automatic qualifying spot from that heat, behind Kenya's Winny Chebet, Poland's Angelika Chichocka and Morocco's Rabab Arafi.
USA's Kate Grace, Canada's Nicole Sifuentes and Australia's Zoe Buckman – the latter who had tracked Judd for much of the race – took non-automatic qualifying spots.
World indoor champion Sifan Hassan – the fastest in the world this year – won heat two. Content to bide her time for much of the race, the versatile Dutch runner left it late to make her move, moving through fast on the home straight to win in 4:08.89, covering the final 300 metres in 45.05.
USA's Jenny Simpson, Ethiopian Gudaf Tsegay and British record-holder Laura Muir all finished within a tenth of the winner, with Morocco's Malika Akkaoui and Germany's Hanna Klein taking the two other automatic qualifying spots. Just half a second covered the top six places.
Kenya's Olympic champion Faith Kipyegon took the third heat in 4:03.09. Colombia's South American 1500m and 5000m champion Muriel Coneo had led the field in the early stages, with Germany's European under-23 champion Konstanze Klosterhalfen taking over through 800m in 2:12.81. The 20-year-old still led at the bell in 3:00.11, but she was closely tracked by Kipyegon and Ethiopia's Besu Sado, who were followed by Sweden's Meraf Bahta and Great Britain's Laura Weightman.
On the final lap, Bahta and Poland's Sofia Ennaoui came through strongly for second and third, while Weightman looked relaxed when clocking 4:03.50 in fourth. Sado finished fifth and although Klosterhalfen faded on the final lap, the young German was rewarded for pushing the pace with a place in the semifinal after taking the sixth automatic qualifying spot from that heat.
Canada's Gabriela Stafford, USA's Sara Vaughn and Great Britain's Sarah McDonald all clocked personal bests in seventh, eighth and ninth respectively, earning themselves places in the semifinal as non-automatic qualifiers.
Emily Moss for the IAAF