Sisson ran 66:52 to take 18 seconds off her own record but finished 2nd to Ethiopia's Hiwot Gebremaryam. Tirunesh Dibaba was never a factor in her return and was 16th in 71:35. In the full marathon, Hitomi Niiya (2:19:24) nearly broke the Japanese record.

• MB: Official 2023 Houston discussion thread
• MB: Sisson 66:52 American Record!

Simpson will make her half marathon debut while Dibaba is running her first race since 2018

A duel between legends was the headliner, but did you know the future greatest marathoner in history ended up making a classic beginning runner's mistake? 2005 World XC also featured an impressive double from Tirunesh Dibaba, an appearance from 15-year-old Aliphine Tuliamuk, and the last world xc appearances for Galen Rupp, Jenny Simpson, and Dathan Ritzenhein 

Keitany returns to defend her title against NYC champ Cheruiyot and they also face Berlin champ Gladys Cherono and Chicago champ Brigid Kosgei. So four out of six of the reigning champs from WMM races will be there.

Gemechu won in 66:50 to beat out Jepkosgei by 6-seconds and her countrywoman Zeineba Yim by 9. Dibaba struggled early and finished back in 6th (68:36). Ethiopia's Andamlak Belihu won the men's race in 59:18 to win over Amdework Walelegn (59:22). USA's Leonard Korir was 6th in 60:12.

And the plan is to do it the optimal way- with a negative split.

Dibaba will be up against former two-time Berlin winner Gladys Cherono, former world champion Edna Kiplagat and Ethiopians Yebrugal Melese (2:19:36) and Aselefech Mergia (2:19:31).

Mary Keitany and Tirunesh Dibaba, two of the greatest women's distance runners in history will chase the greatest women's distance world record on Sunday. Can they possibly break Paula Radcliffe's 2:15:25?

Shalane Flanagan cracks the top 5 as we for the first time exclude from our rankings an athlete, Sarah Chepchirchir, not convicted of a doping offense.

Jordan Hasay has run the #2 time in US history (2:20:57).

 Tirunesh Dibaba wants to lower her 2:17:56 PR, Renato Canova says defending champs Abel Kirui & Florence Kiplagat are around "90%" of where they were last year. *American Sam Chelanga Thinks He Ultimately Can Run At Least 2:06 *American Diego Estrada Says He Can Run 2:07 Right Now (In Monza)

Two-time defending champ Florence Kiplagat is back in Chicago but she's an underdog as Tirunesh Dibaba, arguably the greatest women's distance runner in history, is racing. If they falter, American Jordan Hasay could win but having looked at the stats, we're worried she may never run faster than her debut in Boston. *MB: Will Jordan Hasay ever run faster than her 2:23:00 debut in Boston? Yes or no.

Kimetto and Kirui also face half-marathon WR holder Zersenay Tadese.

This race is fascinating on paper. Dibaba is the GOAT in the event but Ayana is the fastest and current Olympic champ. Who has the edge?

Running history was made today when the greatest field assembled in women's marathoning history battled against each other. Mary Keitany ran the fastest marathon ever in an women's only race and she did so in mind-boggling fashion as she ran the first half more than a minute faster than any woman in history. Tirunesh Dibaba had a historic run as well, putting herself third on the all-time list in 2:17:56. On the American front, Laura Thweatt had a super impressive run, taking almost 3-minutes off her PB to finish sixth in 2:25:38. *MB: Laura Thweatt 2:25:38 in London, #7 all-time US

The London Marathon website has called this "the best elite women’s field ever assembled," and they may be right. There are four sub-2:20 women and four more sub-2:22, including world champ Mare Dibaba, Chicago champ Florence Kiplagat and Berlin champ Aberu Kebede. Plus track studs Tirunesh Dibaba and Vivian Cheruiyot (who is making her debut).

World Half champ Peres Jepchirchir is also in the field while the men are lead by London Marathon runner-up Stanley Biwott, World XC silver medalist Bedan Karoki, Augustine Choge and Solomon Yego (58:44).

The field is stacked as usual with 7 women who have ran under 2:21 and also includes Chicago champion Florence Kiplagat, Berlin winner Aberu Kebede and and former London winners Tigist Tufa (2015) and Aselefech Mergia (2010). Team USA will get some representation from Laura Thweatt and Kellyn Taylor.