The 29-year-old Kenyan, who won her first world title in Osaka in 2007 before finishing second to compatriot Pamela Jelimo at the Beijing Olympics, has looked below her best in the two-lap race, and was even considering switching to the 1 500m in Moscow.
But with Jelimo sidelined with a knee injury Jepkosgei believes she is still strong enough to challenge the mighty Russians in their own backyard in August.
"I am happy about my training and the preparations for the world championships," said Jepkosgei who is included in the provisional squad of 69 athletes which started early residential training for the worlds in Nairobi early this month.
Her qualifying time of 2:00.00 was recorded when she finished eighth and last at the London Olympics last August.
"I am readying myself to run again against the Russian girls - reigning Olympic champion Mariya Savinova and Ekaterina Poistogova (bronze medallist) at home.
"I know it will not be easy but I just need to remain focused and hopefully all will be well," Jepkosgei said.
The athlete, who also won a bronze medal in Daegu two years ago, opted to compete in the shorter 400m as speed work for the 800m during the Kenyan national championships on Friday, but was beaten into second place by African 400m hurdles bronze medallist, Maureen Chelagat.
Jepkosgei will also have to negotiate through the Kenyan national trials in July to make sure of her place in the world championship team.