A preview of this year's edition, including which athletes to watch out for and how to keep in touch with all the action.

John Korir is hoping to become just the sixth male athlete to defend his Chicago Marathon title this Sunday (October 12) but he will not have it all his own way against a strong field.

The Kenyan won by almost two minutes last year in a time of 2:02:44, a mark which put him eighth on the marathon all-time list.

If Korir does cross the finish line tape first again then he will follow in the footsteps of Steve Jones (1984/1985), Luíz Antônio (1993/1994), Khalid Khannouchi (1999/2000), Evans Rutto (2003/2004) and Samuel Wanjiru (2010/2011).

Not only is Korir targeting victory in Chicago but he wants to become the second man in history to run a sub-2:01 marathon. Only the late Kelvin Kiptum, who ran his world record of 2:00:35 in Chicago two years ago, has broken the 2:01 barrier over 26.2 miles.

With two victories out of two this season, Korir's preparation for Chicago couldn't have been better. The 28-year-old won the Boston Marathon with 2:04:45 back in April and followed that up by triumphing over 15km at July's Boilermaker Road Race in New York, running 42:44.

Competition will be fierce in Chicago however and one athlete to watch will be Uganda's Jacob Kiplimo. Back in April, London Marathon event director Hugh Brasher stated that Kiplimo was set for "the most fascinating marathon debut ever", adding that a first legal sub-two hour marathon was "not impossible".

Conditions in London were warmer than usual though and Kiplimo battled the heat to run 2:03:37 for second, placing only behind Sabastian Sawe in the British capital.

The Ugandan demolished the world half-marathon record with 56:41 in Barcelona eight months ago but his move to the marathon was a step into the unknown. Now he has one under his belt there is a feeling, with more conducive conditions for fast times, he can run a lot quicker.

Kenyan trio Timothy Kiplagat, Amos Kipruto and CyBrian Kotut can't be discounted either in Chicago. Kiplagat has the second fastest mark in the field with 2:02:55 and ran that time at last year's Tokyo Marathon, where he finished second to Benson Kipruto.

Like Kiplagat, Amos Kipruto's best of 2:03:13 was also set in Tokyo, with the Kenyan only placing behind Eliud Kipchoge at the 2022 edition. Kipruto also won the 2022 London Marathon so he knows the feeling of topping the podium at a marathon major. Kotut meanwhile has a best of 2:03:22 and placed third at this year's Boston Marathon.

American hopes will likely lie with Conner Mantz, who placed fourth in Boston back in April, finishing just four seconds behind Tanzania's Alphonce Simbu – now the world marathon champion – and Kotut.

Mantz's 2:05:08 on the storied course was the second fastest ever by an American in Boston, only behind Ryan Hall’s 2:04:58 from 2011. There is no doubt that Mantz will be targeting Khannouchi's 23-year-old US marathon record of 2:05:38 in Chicago [Boston is not a record-eligible course, primarily its point-to-point nature and significant net downhill elevation drop].

Britain's Marc Scott is also in the field and will aim to better his best of 2:11:19, set in London last year. Scott has raced lightly in 2025 and had to pull out of this year's London Marathon due to a persistent knee injury. He ran 64:05 for seventh at September's Great North Run.

Ethiopian duo Megertu Alemu and Hawi Feysa are likely favourites for the women's title but there could easily be a surprise winner in Chicago.

Alemu has the quickest time in the field with 2:16:34, a mark she recorded at last year's London Marathon. The 27-year-old placed fourth on that occasion but did make the podium in London three years ago. She won the Valencia Marathon back in December and is yet to compete in 2025.

Her compatriot Feysa boasts a best of 2:17:00 – set at this year's Tokyo Marathon – and is the second fastest overall. Not only did Feysa make the podium in Tokyo – finishing behind Sutume Kebede and Winfridah Moraa Moseti – but she also won the 2024 Frankfurt Marathon.

Don't count out Kenya's Irine Cheptai however, who has experience of making the podium in Chicago. At last year's edition she ran 2:17:51 for third, finishing only behind Ruth Chepng'etich and Kebede.

Chepng'etich ran a world record of 2:09:56 a year ago – which was later certified – but has since been provisionally suspended by the Athletics Integrity Unit (AIU) after testing positive for the banned substance hydrochlorothiazide (HCTZ).

One big unknown before Chicago is how 2023 world 10,000m bronze medallist Ejgayehu Taye will fare in her marathon debut. The Ethiopian arrives in Chicago off the back of a fifth place finish over 25 laps at the World Athletics Championships in Tokyo.

Britain's Calli Hauger-Thackery was initially selected for the marathon in Tokyo but, after gaining selection through the world rankings, decided to instead compete in the 10,000m. This was always likely after Hauger-Thackery signed up for Chicago back in August and she will no doubt hope to better her best of 2:21:24 from Berlin last year.

Hauger-Thackery currently lies second on the UK all-time marathon rankings behind Paula Radcliffe and is aiming for a sub-2:20 run in Chicago. Philly Bowden was on the entry lists but pulled out this week after an MRI scan revealed she had a fracture in the bone on the inside of her right knee (medial femoral condyle).

In the wheelchair divisions, defending champions Catherine Debrunner and Marcel Hug will be tough to beat. The Swiss duo have an imperious record in Chicago, with Debrunner chasing her third consecutive win and Hug the heavy favourite to secure his seventh title.

Chicago Marathon timings:

7:20 CDT/13:20 BST – Start of men's marathon wheelchair division
7:21 CDT/13:21 BST – Start of women's marathon wheelchair division
7:30 CDT/13:30 BST – Start of men's/women's elite fields

For UK viewers, you can watch highlights of the 2025 Chicago Marathon on TNT Sports 4 from 22:00 to 23:00 BST on October 13. 

These are the full elite fields for the Chicago Marathon below:

Men

John Korir, KEN, 2:02:44 (Chicago, 2024)
Timothy Kiplagat, KEN, 2:02:55 (Tokyo, 2024)
Amos Kipruto, KEN, 2:03:13 (Tokyo, 2023)
CyBrian Kotut, KEN, 2:03:22 (Berlin, 2024)
Bashir Abdi, BEL, 2:03:36 (Rotterdam, 2021)
Jacob Kiplimo, UGA, 2:03:37 (London, 2025)
Philemon Kiplimo, KEN, 2:04:01 (Hamburg, 2025)
Geoffrey Kamworwor, KEN, 2:04:23 (London, 2023)
Huseydin Mohamed Esa, ETH, 2:04:39 (Chicago, 2024)
Conner Mantz, USA, 2:05:08 (Boston, 2025)
Daniel Ebenyo, KEN, 2:06:04 (Chicago, 2024)
Galen Rupp, USA, 2:06:07 (Prague, 2018)
Hiroto Inoue, JPN, 2:06:14 (Tokyo, 2025)
Zouhair Talbi, MAR, 2:06:39 (Houston, 2024)
Matt Richtman, USA, 2:07:56 (Los Angeles, 2025)
Ryan Ford, USA, 2:08:00 (Boston, 2025)
Rory Linkletter, CAN, 2:08:01 (Seville, 2024)
CJ Albertson, USA, 2:08:17 (Chicago, 2024)
Hideyuki Tanaka, JPN, 2:09:27 (Tokyo, 2025)
Patricio Castillo, MEX, 2:10:40 (Seville, 2023)
Marc Scott, GBR, 2:11:19 (London, 2024)
Colin Mickow, USA, 2:11:22 (Chandler, 2020)
Kevin Salvano, USA, 2:11:26 (Chicago, 2023)
Nick Hauger, USA, 2:11:55 (Sacramento, 2024)
Robert Miranda, USA, 2:12:07 (Sacramento, 2024)
Afewerki Zeru, USA, 2:18:54 (Porto, 2023)
Casey Clinger, USA, Debut
Tai Dinger, USA, Debut

Women

Megertu Alemu, ETH, 2:16:34 (London, 2024)
Hawi Feysa, ETH, 2:17:00 (Tokyo, 2025)
Irine Cheptai, KEN, 2:17:51 (Chicago, 2024)
Bedatu Hirpa, ETH, 2:18:27 (Dubai, 2025)
Haven Hailu Desse, ETH, 2:19:17 (London, 2025)
Mary Ngugi-Cooper, KEN, 2:20:22 (London, 2022)
Calli Hauger-Thackery, GBR, 2:21:24 (Berlin, 2024)
Lindsay Flanagan, USA, 2:23:31 (Chicago, 2024)
Natosha Rogers, USA, 2:23:51 (Nagoya, 2025)
Florencia Borelli, ARG, 2:24:18 (Seville, 2024)
Gabi Rooker, USA, 2:24:29 (Chicago, 2024)
Dakotah Popehn, USA, 2:24:40 (Chicago, 2023)
Melody Julien, FRA, 2:25:01 (Valencia, 2023)
Aubrey Frentheway, USA, 2:27:14 (Duluth, 2025)
Maggie Montoya, USA, 2:27:50 (Rotterdam, 2025)
Loice Chemnung, KEN, Debut
Ejgayehu Taye, ETH, Debut
Emily Venters, USA, Debut