NAIROBI, Nov. 24 (Xinhua) -- World Half Marathon record holder Joyceline Jepkosgei has warned she is back to her optimum form that saw her shutter the world mark in 2017.

With just under two weeks before the Kenyan star launches her marathon debut show in Honolulu in the U.S. on Dec. 9, Jepkosgei has sounded the alarm when she won the Kenya Defense Forces cross country title in Nairobi on Friday.

It was Jepkosgei's fourth race this year. "I was using this race for speed work. It is time for my bid switch from half marathon to full marathon next month," said Jepkosgei.

"I just want to finish and feel the pain of the marathon. I'm told the conditions in Honolulu will be warm, which is good."

Jepkosgei says she hopes to get a surprise birthday present in Honolulu by winning the race. Her birthday is on Dec. 8.

Jepkosgei has however said she is not keen to make the Kenya team to the World Championships too soon.

She however, harbors the dream of representing the country and the 2020 Olympics in Japan look an ideal stage for her big race.

"First is to see how the body will respond on my first marathon. Then irrespective of the results, I will build on it with more experience and hopefully be ready for the Olympics in 2020," she added.

Last month Jepkosgei won another half marathon in Eldoret. Jepkosgei finished third in a time of 68:10 at this year's Great North Run in Newcastle, England.

Injury concerns, however, have limited the Kenyan's participation in international competition, but she believes she is getting better.

In May, Jepkosgei finished second at the Manchester 10km run behind Ethiopia's Tirunesh Dibaba. But her win two weeks to Honolulu Marathon debut has instilled an invincible feeling in the Kenyan.

"The weather conditions here were hot and humid, similar to what I expect in Honolulu. The course was good. I trained well for this race and I was confident of winning the title ahead of the race. It is always important to train hard and that way, you fear nobody, whoever they are, on the race day," she added.

Jepkosgei's coach and husband Nicholas Koech says he is certain the 24-year-old will weather the storm and write history, like many before her, to win the marathon on her debut.

"I want her to have an impact when she transits to the marathon," he said.