The BOLDERBoulder, America’s All-Time Best 10K, announced today the official lineup for the 2025 International Team Challenge, set to take place on Memorial Day, May 26, 2025. Professional runners from across the globe will compete in this prestigious event, representing their countries in both the men’s and women’s divisions.
In the men’s race, defending champion Conner Mantz returns to the BOLDERBoulder with his sights set on a third consecutive victory, following dramatic wins in 2023 and 2024. In 2023, Mantz surged from fourth place in the final 800 meters to claim the title. Last year, he entered Folsom Field neck and neck with Eritrea’s Yemane Haileselassie but found another gear on the stadium floor, pulling ahead to win by two seconds. Haileselassie returns in 2025, determined to break Mantz’s streak. Also eyeing the top spot is Ethiopia’s Addisu Gobena, who edged out Mantz in a thrilling photo finish at the Houston Half Marathon in January—both clocking 59:17, with Mantz setting a new American record in the process. Other top contenders include Ethiopia’s Haymanot Allew, who ran 2:03:31 to place third at the 2024 Berlin Marathon, and American standouts Hillary Bor, Joe Klecker, Drew Hunter, Biya Simbassa, and Aidan Reed. All six American men in the field rank among the top 12 U.S. performers of all time at the 10-mile distance.
The women’s field is headlined by defending champion Grace Loibach Nawowuna of Kenya, who dominated last year’s race in 32:45 – the ninth-fastest time in BOLDERBoulder history. Nawowuna brings world-class credentials, including a 10K personal best of 29:47 and a 1:06:23 half marathon from earlier this year. She’ll be challenged by fellow Kenyan teammate Diana Chepkorir, another sub-30 10km runner. Ethiopia’s Meseret Belete will lead a formidable Ethiopian squad; she recently won the Daegu Marathon and has a marathon best of 2:18:03. The United States will field two teams, with Team USA Red led by 2023 BOLDERBoulder champion Emily Durgin. She is joined by Aubrey Frentheway and Molly Grabill. Grabill won last year’s citizen’s race in a record time of 33:39. Team USA White features an all-University of Colorado alumnae lineup: Mckenzie Caldwell, Carrie Ellwood, and Makena Morley. Earlier this month, Ellwood set a new 25 km American record.
Men’s Teams
Seven international men’s teams will line up on race day:
- USA Red – Hillary Bor (35), Conner Mantz (28), Biya Simbassa (31)
- USA White – Drew Hunter (27), Joe Klecker (28), and Aidan Reed (27)
- Eritrea –Yemane Haileselassie (27), Amanuel Mesel (34), Tuemay Tsegay (29),
- Ethiopia – Haymanot Allew (27), Asefa Boki (27), Addisu Gobena (20)
- Kenya – Daniel Simyu Ebenyo (29), Athanas Kioko (30), Lawrence Kipkoech (32)
- Mexico – Jorge Cruz (28), Evert Silva (25), Abraham Hernández (29)
- Morocco – Abdelkarim Abouzouhair (27), Abdelkarim Ben Zahra (26), Ayoub Karym (24)
Women’s Teams
Six teams will compete in the women’s division:
- USA Red – Emily Durgin (30), Aubrey Frenthaway (25), Molly Grabill (32)
- USA White (CU Alumni Team) – Mckenzie Caldwell (28), Carrie Ellwood (31), Makena Morley (29)
- Ethiopia – Meseret Belete (25), Ayal Dagnachew (23), Alem Tsadik (27)
- Kenya – Diana Chepkorir (22), Grace Loibach Nawowuna (21), Sarah Naibei
- Mexico – Anahi Alvarez (23), Adela Hororato (20), Natali Mendoza (29)
- Morocco – Kaoutar Farkoussi (29), Rahima Tahiri (26), Hasne Zahi (34
The full entry list with athlete profiles can be found here: LINK
The women’s race will start at 11:11 AM and the men’s race at 11:22 AM. After looping through the streets of Boulder they will finish in a full stadium at the University of Colorado’s Folsom Field scheduled ahead of the Memorial Day Tribute.
Live coverage of all BOLDERBoulder events begins at 6:45am MT on YouTube and coverage of the professional races and Memorial Day Tribute will be aired live in the greater Denver metropolitan area on Denver7 (ABC) from 11am–12:45pm MT.
2025 STORY LINES
WHEELCHAIR RACE (6:45am)
Men
- Daniel ROMANCHUK (Champaign, IL), arguably the greatest USA Wheelchair racer in history, takes aim at Saul Mendoza’s 21-year-old record of 19:45; Romanchuk is a Paralympian gold medalist (2x) and since 2019 has won 9 World Marathon Majors -Boston (2x), New York (3x), Chicago (3x), and London (1)
Women
- Kendall GRETSCH (Colorado Springs), a four-time Paralympian gold medalist (winner and summer), seeks her third BB10K title in four years.
CITIZEN’S RACE (1st of 95 waves – 6:50am)
- Bacon vs. Banana – Last year Steven Goldy finished fifth in the Citizens race running in a banana costume. This year he will be challenged by Ryder Searle (2nd last year) who will toe the line wearing a bacon costume.
- Defending champions Aidan Reed and Molly Grabill will not be defending their titles as they have been “called up” and will run in the Professional races later in the day.
- Last year 842 runners broke 40 minutes (most of any other 10 km in the country)
- Special Recognition/Awards
- Single Age medals to top 15 each age (not age division) – ages 6 to 100
- Sub-40 Shirts – Athletes who break 40 minutes receive a commemorative Nike shirt
- Ageless Wonder Shirts – runners who run faster than their age receive a commemorative shirt
- BOLD SQUAD – Over 4000 runners under the age of 14 will be competing and are members of the BOLD SQUAD
- BOLDEST – 47 runners running have run EVERY BOLDERBoulder and are the BB BOLDEST
- 134 runners will be celebrating their Birthdays on Monday
- 11 Olympians (both Summer and Winter) will be running in the Citizens race
- Kylie Mantz (A678), Conner’s wife, is running in the A Wave
- FORTITUDE Mile Challenge presented by RUNNA – 4,483 participants in 2024 raced final mile faster than each of the previous 5 miles (not negative splits)
PRO WOMEN (11:11am)
- 1st Bank “First to Folsom” Prime (1st to cross the Prime “finish line – $1000)
- Grace Loibach NAWOWUNA (KEN) returns to defend her title she won last year running the 9th fastest time in race history (32:46)
- Diana CHEPKORIR, who is based in Boulder (On Athletics Club), ran ran 29:57 (10 km) on the roads in Feb, 24 but only 1:09 (half marathon) in January in Houston and was fifth a few weeks ago at the Bloomsday Lilac 12 km in Spokane – if we get the 29:57 Diana she could content for the win.
- Meseret BELETE (ETH) – 2:18:21 marathon PR (’23); Won the Daegu Marathon in February
- Emily DURGIN (USA Red; Flagstaff, AZ) was the convincing winner here 2 years and finished 5th last year. This is her first race of the year.
- Aubrey FRENTHEWAY (USA Red; Salt Lake City) A young up in coming star. Graduated from BYU in 2023. Recently finished 4th at the USA 10 Mile Championships running 51:58 (#9 U.S. all-time)
- Team USA White – All University of Colorado alumnae squad (Mckenzie CALDWELL (’19), Carrie ELLWOOD (’17), Makena MORLEY (‘20)
- Ellwood recently set the 25 km American record
PRO MEN (11:22am)
- 1st Bank “First to Folsom” Prime (1st to cross the Prime “finish line – $1000)
- Conner MANTZ attempts to three-peat after winning the past 2 years
- Conner MANTZ vs Addisu GOBENA (Eth) – the rematch from Houston where they both clocked 57:17
- Daniel Simyu EBENYO (KEN) 26:56 PR; Silver Medalist in the 10,000m at the 2023 World Championships
- Haymanot ALLEW (ETH) – 3rd at 2024 Berlin Marathon (2:03:21); three career sub-2:06 marathons
- Strong USA men’s teams (all six are in the top-12 U.S. 10 mile all-time)
- Team USA Red – Conner Mantz, Hillary Bor, and Biya Simbassa
- Team USA White – Drew Hunter, Joe Klecker, Aidan Reed
- Reed makes Pro field debut after winning Citizens Race last year
- Hunter’s father, Marc, won the 1980 BB10K
- Last year Team USA Red won the team title (Team USA White 2nd; Kenya 3rd)
About BOLDERBoulder
Founded in 1979, the BOLDERBoulder has grown into one of the largest 10K races in the United States, attracting over 50,000 runners, joggers, walkers, and spectators annually. With its unique blend of elite competition, community celebration, and Memorial Day tributes, it remains a must-attend event in the international running calendar.