(L-R) Natalia Rodriguez of Spain, Christin Wurth-Thomas of the United States and Natalya Evdokimova of Russia compete in the women's 1500m semi-finals in Berlin (© Getty Images)
The Olympic champion Nancy Langat of Kenya and World No.2 Anna Alminova of Russia both crashed out of the competition after both fell victim to a slow-run second semi-final.
Nerves would not have been helped by the 40-minute delay to the start of the semi-finals following the earlier deluge but that should not be used as an excuse for the aforementioned Langat and Alminova.
However, there was no such mishap for defending champion Maryam Jamal who won a lightning fast first heat in 4:03.64 from Spanish record holder Natalia Rodriguez (4:03.73).
A measure of the quality of the race was that Jamal's time was the second fastest ever women's 1500m winning time at a World Championships semi-final.
Great Britain's Lisa Dobriskey, the Olympic fourth place finisher, secured the third qualification spot in 4:03.84 with the final two automatic places going to Christin Wurth-Thomas of the USA (4:04.16) and 18-year-old Kalkidan Gezahegne of Ethiopia in 4:04.75.
Meanwhile, Russia's Natalya Evdokimova was rewarded for setting a swift pace for much of the race to earn a passage through to Sunday's final. She earned one of the two fastest loser spots in sixth (4:04.93) with Poland's experienced Lidia Chojecka earning the other in seventh (4:06.53)
Evdokimova raced to the front as the 13 women set off at high pace from the gun. The race then settled down with the Russian taking them through 400m in a handy 1:03.58 and 800m in (2:11.84). All the time Wurth-Thomas, a natural front runner, was on her shoulder threatening to take the lead with Jamal lurking with intent close behind.
With 500m remaining Wurth-Thomas could wait no longer and hit the front, her pitter-patter stride trying to break free from the rest of the field. At the bell nine women still had a realistic chance of qualifying, however, entering the turn the lead five had opened up a significant gap on the remainder.
It was just left for Jamal to canter to the heat win from Rodriguez, Dobriskey and Wurth-Thomas with Gezahegne holding off a late charge from Evdokimova.
In a much slower second semi-final Gelete Burka of Ethiopia, who many view as the main danger to Jamal, controlled the race from the front to take victory in 4:10.19. Behind her Morocco's Mariem Alaoui Selsouli was also an impressive looking qualifier in second (4:10.46).
Anna Willard (4:10.47) and her compatriot Shannon Rowbury (4:10.51) ensured the US had qualified three women for the final in this event for the first time in World Championship history. Spain's Nuria Fernandez enjoyed a belated birthday present three days after turning 33, to secure the fifth and final automatic spot.
There was no place, however, for Langat, the Olympic champion who missed out on the last lap burn up to finish seventh in 4:11.00. Mystifyingly, Alminova who has ran under 4:00 this season was even further back. She appeared to run a tactically naive race - and wound up 10th in 4:12.55.
The Olympic silver medallist Iryna Lishchynska, who was prominent in the early stages, abandoned attempts to complete the race and also failed to advance.
By contrast to the first race the field was content to amble around at a relatively sedate pace and Burka took them through 400m in 1:07.41. She was still at the head of affairs a lap later, reached in 2:20.04, half a stride ahead of Lischynska.
The race followed a rather featureless pattern with Burka leading ahead of Selsouli at the bell, although 11 women were tightly bunched.
Down the back stretch Alminova, who was rarely prominent, started to drift out of contention, although nine women were still in the hunt coming down the home stretch.
Burka was always in control and crossed the line barely breathless to take the heat win. Selsouli looked similarly comfortable in second. While the US duo - Rowbury and Willard also safely progressed. Fernandez, ensured two Spaniards made it through to the final. A word also for Nikki Hamblin of New Zealand, who performed with distinction to finish sixth in the semi-final in 4:10.96. She just missed out on a qualifcation spot by one place, however.
Steve Landells for the IAAF
