Caster Semenya has been the dominant force on the circuit again this year, extending her victory streak to 28, dating back almost three years.
In the process, the South African took the Commonwealth Games, African and IAAF Diamond League titles and improved her national record to 1:54.25, making her the fourth fastest of all time.
Hoping to at least challenge Semenya, teammate Francine Niyonsaba of Burundi also has a string of fast times this year. The world indoor champion's season's best of 1:55.86 makes her the second fastest in the world in 2018.
The Americas team will hope for a strong showing in the event with the third and fourth fastest women of 2018. Natoya Goule of Jamaica has improved by more than three seconds to take the national record to 1:56.15. World indoor silver medallist Ajee Wilson of the US is only marginally slower this year with 1:56.45. Both women finished ahead of Niyonsaba at the recent IAAF Diamond League final, with Wilson taking second and Goule third.
Ukraine's two-time European champion Nataliya Pryshchepa leads the Europe squad.
Pawel Jackowski for the IAAF