Brigid Kosgei plans an aggressive first half at the Chicago Marathon. She requested pacers to lead her through 65:30, per Marathon Handbook. This is 89 seconds faster than her 2019 world record halfway.

Kosgei, 32, returns to Chicago after setting the world record of 2:14:04 in 2019. She won the Tokyo Marathon in March with a more conservative start. Her Tokyo halfway split was 1:07:37. Read more racing coverage.

Kosgei's half-marathon best is 1:04:49, but she aims for a quicker 65:30 in Chicago. Hawi Feysa, last year's winner, also targets the same split. Assefa ran 1:04:57 in Berlin, the third-fastest opening half ever. Related: Brigid Kosgei Returns to Chicago Marathon with Tokyo Record Fresh.

This original Runner World brief is based on reporting from Marathon Handbook. Visit the source for its complete reporting, context and any later corrections.