Jacob Kiplimo goes into Sunday's Bank of America Chicago Marathon as the heavy favourite. The Ugandan won here last October in 2:02:23, more than a minute clear of Amos Kipruto, and has improved with each of his three marathons, running 2:03:37 in London in 2025 and then 2:00:28 for third in London this April. That time is seven seconds inside the Chicago course record of 2:00:35 set by Kelvin Kiptum in 2023, and puts him third on the world all-time list.
Kiplimo has not raced since London, which is the one question mark that LetsRun's preview raises. He has said that his preparation had given him a lot of confidence and that having raced the course before is a real advantage. He is also a former half marathon world record holder with 57:20 in Lisbon, and has won three consecutive World Cross Country titles.
Kipruto, the 2022 London champion, is the most credible challenger. The Kenyan ran a personal best of 2:01:39 in London in April and was the runner-up here last year. Behind them, the Ethiopian trio of Milkesa Mengesha (2:03:17), Tadese Takele (2:03:23) and Asrar Hiyrden (2:03:59), together with Kenya's Daniel Mateiko (2:03:44), give the race depth, with six men in the field having run inside 2:04. Alex Masai and Bashir Abdi have withdrawn, while Tomoki Ota, Kieran Tuntivate and Adriaan Wildschutt are listed as marathon debutants.
The American record is also in play. Conner Mantz set the current mark of 2:04:43 in Chicago last year, and Charles Hicks arrives with a best of 2:04:35 from Boston, seventh in April. Clayton Young (2:05:41) is hoping to chase the record despite a torn hamstring, and Vincent Mauri (2:05:54) is also in the field, alongside 2017 champion Galen Rupp.
The world record of 1:59:30 looks unlikely on a warm morning. The forecast is for roughly 59°F at the 7:30am start, rising to about 62°F by the time the leaders finish, under cloud with light winds. Those conditions should allow a fast race without being ideal, and the pacing will matter: a 2:03 lead pace would favour the strongest finishers, while anything quicker risks turning the race into one of attrition.