World 800m bronze medalist Ferguson Rotich ran the fastest time outside the Olympics to win heat one to storm into the semi-finals and join compatriots James Saruni and Emmanuel Korir.
Rotich clocked 1:43.75 to cross the line ahead of Peter Bol of Australia who timed 1:44.13 and Giles Elliot of Great Britain who finished at 1:44.49.
National trials winner Saruni on the other hand finished second in heat four behind Nijel Amos of Botswana to make it to the semis.
Korir was the winner of heat six in a time of 1:45.33 to finish ahead of Borkowski Mateusz of Poland who placed second at 1:45.34.Hoppel Byrce of the United States completed the top three after timing 1:45.54.
The three will be aiming to retain the gold medal won by David Rudisha in Rio 2016.
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