Kenyan Moses Mosop won the 34th Chicago Marathon on Sunday, surging away from the field with 10 kms to go and setting a course record of two hours five minutes 37 seconds.
Liliya Shobukhova of Russia won the women's competition for the third straight year, in 2:18:20. Both winners' times were unofficial.
Mosop, who lost the Boston Marathon to compatriot Geoffrey Mutai by four seconds in April, cruised over the last nine kms and took four seconds off the course record set by Sammy Wanjiru in 2009.
"I'm very happy about my job today," Mosop told NBC television, adding that a leg injury had limited his training.
Kenyans filled the podium with Wesley Korir finishing second, 38 seconds behind, and Bernard Kipyego taking third.
Ethiopian track runner Ejegayehu Dibaba, who was making her marathon debut, ran alongside Shobukhova until about the 24-km mark before slipping off the pace. She finished second in 2:22:09. Kayoko Fukishi of Japan was third.