Three-times world champion Asbel Kiprop put in a blistering last lap on Thursday to reach the Olympic 1,500 metres final as fellow Kenyan Ronald Kwemoi advanced with the quickest time in winning the second semi-final.
Kiprop, the 2008 Olympic champion, ran the last lap of the opening semi-final in 52.93 seconds, sweeping past the field on the back straight and taking the lead off the final bend to cross the line first in three minutes, 39.73 seconds.
Defending champion Taoufik Makhloufi of Algeria, who picked up a silver in the 800 metres in Rio, was second in 3:39.88 with New Zealand's Nick Willis third (3:39.96).
The second heat was quicker and Kwemoi only secured victory with his final kick down the home straight, outpacing Ayanleh Souleiman and American Matthew Centrowitz to reach the line in 3:39.42.
Djibouti's Souleiman clocked 3:39.61 while American Centrowitz crossed in 3:39.61.
Centrowitz's compatriot Robby Andrews qualified in fifth place in the second semi-final but stepped off the track in the run to the line and could face disqualification.