At the age of 21, Salwa Eid Naser of Bahrain became the third fastest female 400m runner in history tonight as she earned gold in 48.14 – almost a full second swifter than her previous best of 49.08 and the fastest run for 34 years.
For a while after the race, as the slight figure of the 2017 silver medallist set off on a victory lap that few expected her to be making, the seemingly unbeatable Rio 2016 champion Shaunae Mille-Uibo of The Bahamas sat, stunned, at the side of the track, a national flag draped around her.
She was clearly trying to process the fact that she had just taken more than half a second off her NACAC Area record of 48.97, clocking 48.37, only to find herself in silver medal position.
The super-fast nature of this final was underlined by the fact that the three runners behind the 25-year-old Bahamian set personal records.
Shericka Jackson of Jamaica took bronze in 49.47, Wadeline Jonathas of the United States was fourth in 49.60, and her compatriot, defending champion Phyllis Francis, was fifth in 49.61.
Naser, who had already won a bronze in the 4x400m mixed relay, had impressed with her smooth progress in the semi-finals, where she clocked 49.79.
But Miller-Uibo – larger and more powerful than her young rival – topped the qualifiers with 49.66 and had appeared to jog home in impressive fashion.
“This is crazy,” said Naser. “I already did the mixed relays and I was just hoping for the best, but now I’m world champion. I’m really short of words to describe how I’m feeling, it’s just crazy. I’m screaming I’m so happy.
“It’s been so tough with all the training and injuries, and getting there has been hard.
“I didn’t want to chase because I’m so used to chasing all the time, so I had to go out fast, and I just kept going. To cross the line and see that I am world champion in that amazing time, I just couldn’t believe it.”
Asked if she might now contemplate breaking the world record of 47.60 set in 1985 by Marita Koch of East Germany, she responded: “Anything is possible”.
Miller-Uibo commented: “To run a time like that and not to win is incredible. I think I let her get away from me a little too much but I got a huge personal best so I have to be happy with that. She ran a crazy race.”
Despite the top class field, this was always a duel between two runners, one apparently in her prime, one apparently reaching it.
When Naser, two lanes inside Miller-Uibo in lane five, moved up level to the Olympic champion around the crown of the top bend it looked as if she was making a bold move to vary the tactics and see if she could bring some pressure to bear upon the favourite.
But as the field hit the straight it became increasingly clear that this was no bold goading, but an inexorable progress towards a first global gold. Miller-Uibo responded, closing the gap to around a couple of metres, but that was how it stayed as they crossed the line to roars of surprise and excitement from a full and reverberating stadium.
Mike Rowbottom for the IAAF