Kiptum's reported 4:21 19th mile and 4:18 22nd mile were the two fastest splits ever recorded in a marathon, but after an investigation by LetsRun.com, race organizers have confirmed discrepancies with those splits.

Kiptum, who regularly runs 150+ miles a week, runs so hard in training that his coach Gervais Hakizimana wants him to slow down: "I told him that in five years he would be done, that he must calm down to last in athletics."

Mantz and Young ensured at least two Americans will be at Paris 2024. Galen Rupp was on track for the standard late but faded and ran 2:08:48 in his return.

Kiptum, who had never run a marathon 12 months ago, now owns three of the six fastest times ever.

Plus Conner Mantz has thoughts on the Olympic Marathon Trials and the qualifying system.

With temps in the 40/50s on Sunday, Kenyans Kelvin Kiptum and Ruth Chepngetich have set their sights on the course records -- and maybe more.

Rupp says he has overhauled his form after years of injury issues -- "I hate going back and looking at videos of myself running last year."

Can Ruth Chepngetich, who ran 2:14:18 in Chicago last year, get close to Tigst Assefa's 2:11:53 WR? How will Sifan Hassan do after her World Championship triple three weeks ago?

Conner Mantz and Galen Rupp lead a strong US field; what can Kiptum do for an encore after running 2:01 in his first two marathons?

Kelvin Kiptum, Conner Mantz, Emma Bates, and Galen Rupp were among the notable names announced by Chicago on Tuesday.

Hassan took down one of the gretest marathon fields in history in London but she'll have her hands full with defending champ Ruth Chepngetich (2:14:18 pb), just 6 weeks after Worlds.

Chepngetich is now #2 all time, 14 seconds shy of Brigid Kosgei's world record.

Can Ruth Chepngetich & Seifu Tura repeat? Who are the Americans to watch outside of Mantz & Sisson? And who is Haven Hailu?

Emily Sisson hasn't raced a fast marathon in years. Can she get the American record in her return to the 26.2 distance? "We’re hoping around 69:30 [for a halfway split]," Treacy said. "Get to 20 miles, see where you are, see how you’re feeling and then hang on or pick it up."

• MB: Emily Sisson's buildup has been spectacular. She plans on going out in 69:30. Will she get the AR?

It's not very often that an American with multiple NCAA crowns and a 13:10 5000 pb makes his marathon debut in the prime of his career, but that's happening this week for Conner Mantz. Mantz's debut is the biggest for an American since Galen Rupp.

• MB: Conner Mantz says 4:46 pace at altitude feels "comfortable" - Indicates he will go out in 1:03 at Chicago Marathon

We can't ever remember seeing this happen in an elite marathon and doubt we'll ever see it again.

Ryan is bullish on Sara's fitness heading into the 2021 Chicago Marathon - "She’s definitely done workouts that she’s never been able to do before and [she’s] super confident, feeling great" - but acknowledges the warmish forecast may take the AR off the table.

We share our six biggest storylines with you and introduce you to the new men's favorite - Reuben Kipyego - whom we just learned was running the race today.

Just as he did in Boston earlier this year, Lawrence Cherono won a thrilling sprint finish for the title today in Chicago. Meanwhile, former NOP teammates Mo Farah and Galen Rupp both struggled but 10 Americans broke 2:12.