Miller-Uibo had opted not to double up with the 200m, prioritising the one-lap event in which she took gold at the Olympics three years ago.

Naser has missed out on a place in the final of that event, having run a PB of 50.88 in the semi-final, but since then she has become one of the world's premium 400m runners.

World Championships
I am a clean athlete, says Hassan
05/10/2019 AT 22:27

The Bahraini runner picked up a world silver in London behind Phyllis Francis, who also ran a lifetime best that was only good enough for fifth on the night, and ran out of her skin to knock nearly a second off her own mark.

Miller-Uibo's 48.37 was the sixth fastest time ever and she was closing on the 21-year-old but could do nothing to stop Naser streaking away in a time of 48.14, a time that has only been bettered by two women ever - Marita Kock and Jarmila Kratochvilova - and by no-one since 1985 when the former set the world record.

Each of the top-five runners ran their best ever times with Shericka Jackson of Jamaica winning yet another bronze medal over one lap to go with her world medal from 2015 and Olympic gong a year later.