NAIROBI, Oct. 3 (Xinhua) -- Two-time Chicago Marathon champion Florence Kiplagat of Kenya will take on compatriot Brigid Kosgei as she eyes a third win in the USA city on Sunday.

Kiplagat, a former world half marathon record holder, has struggled to regain fitness after she suffered career threatening muscle cramping in last year's Chicago Marathon race.

Kiplagat dropped out of the race after 25km mark, citing a muscular injury that ultimately prevented her from defending her Barcelona Half Marathon title in March.

She has not competed in 2018, so this year's race in Chicago will mark her return to competition.

"I have two battles to fight. The obvious one against other athletes to win in Chicago and the personal fight inside me on whether I am back to my best and capable of racing at the top level again," Kiplagat said in Nairobi as she jetted out to USA.

Kiplagat is the 19th fastest woman in history over the marathon distance with a personal best of 2:19:44 from Berlin in 2011.

She has adopted an aggressive front-running style that saw her win in Chicago in 2:21:32 two years ago, which was the thirteenth fastest female time in Chicago Marathon history (now the 16th fastest time) and the fifth fastest time run in 2016.

However, she will face stiff challenge from Kosgei, who held on to clinch silver medal behind eventual winner Tirunesh Dibaba of Ethiopia last year.

There is also two-time podium finisher Birhane Dibaba (Ethiopia) in a women's list that has nine runners, who have run 2:25:00 or faster.

"My focus on Sunday is to finish in first position," said Kiplagat. "But I have been out for long and finishing is important for me."