Eliud Kipchoge has the world record (2:01:39), an Olympic gold medal, and he’s won eight World Marathon Major titles. What he hasn’t done at the 26.2-mile distance yet, though, is break the two-hour barrier. He’ll give it another try on Saturday in Vienna, starting at 8:15 a.m. local time (2:15 a.m. eastern time in the U.S.). The exact start time was decided on Friday afternoon by the “Performance and Meteorology” teams, based on their predictions of the optimal weather conditions.

Kipchoge, 34, of Kenya, came close to breaking two hours in 2017, during the Nike-sponsored “Breaking 2” event on a car racetrack in Monza, Italy, when he crossed the line in 2:00:25. Like that event, this attempt will not be record-eligible because of the number of pacemakers involved and the ability to take hydration and fuel delivered by supporters on bikes, among other variables.

INEOS 1:59 Challenge Pacemakers / photo: Bob Martin for The INEOS 1:59 Challenge

The run in Vienna is sponsored by INEOS, a chemical producer based in the U.K, and dubbed the “1:59 Challenge.” It will utilize 41 pacemakers who will cycle in and out as teams. American athletes slated to take part include Matthew Centrowitz, Hillary Bor, Bernard Lagat, Lopez Lomong, Shadrack Kipchirchir, Stanley Kebenei, and Paul Chelimo. A number of Kipchoge’s countrymen and training partners will accompany him, and other notables such as 12:43 5,000m runner, Ethiopian Selemon Barega, and the three Ingebrigtsen brothers of Norway, European champions all. 

One major difference between the attempts is that Vienna’s course is on public streets and spectators are encouraged to attend. This, according to Patrick Sang, Kipchoge’s coach, could help his chances.

“One element that is very important for Eliud is the crowd,” Sang said in a written statement. “So please, come and support Eliud on the 12th October and cheer him on to help him make history.”

Ineos 1:59 Challenge Course
Ineos 1:59 Challenge Course

The course is a 9.6K circuit repeated 4.4 times. The two turns utilize wide traffic roundabouts and 90 percent of the route is straight.

If you don’t happen to find yourself in Austria on Saturday, you can still watch. In the U.S., NBC will air it live on the Olympic Channel and it can also be watched live (for free) on YouTube.