Sum, who is favourite to win gold in Friday’s finals, completed a gun to tape victory in the first semi in 2:01:38 to inch closer to realising her dream to add the Club Games crown to her World title.
Canadian Melissa Bishop and Australia’s Angie Smit followed the Kenyan after she dropped them with 50m to go.
The second semi saw veteran Jepkosgei’s ambitions of reclaiming the honours she won in Melbourne 2006 end after finishing seventh in 2:04.60.
Earlier, she had posed on her FaceBook page, “God, take this flu away because I want to run in the final,” indication she was indisposed as she came for the race.
Calvin Nkanata’s hope of making his first finals in Kenyan colours in the men’s 200m went up in smoke after missing the automatic qualification by a whisker whilst finishing third in the semis in 20.65.
In cycling men’s individual time trial, veteran David Kinja and John Muya who were in the top five leading pack in the early exchanges found the going tough with Muya fading to 25th in 56:47.69, a place above Kinja who clocked 57:10.11.