Boulder, CO – 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.
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.