Running for the world record at Sunday’s 44th BMW Berlin Marathon, Ethiopia’s Kenenisa Bekele and Kenya’s Eliud Kipchoge and Wilson Kipsang will summon near-super human strength, speed and endurance developed over years of dedicated training. The time they hope to break, 2:02:57 by Kenya’s Dennis Kimetto, was set in Berlin in 2014 and both the athletes and the race organizers all see Kimetto’s mark as breakable.

“I am hoping for good weather, then it’s up to these guys,” race director Mark Milde told Race Results Weekly. “I think we prepared everything in a way that is the best possible situation for them, and then it’s up to them.”

That, however, is only true in part. The three protagonists will also depend on a trio of pacemakers to lead them through Berlin’s streets for nearly three quarters of the course at the right pace, not too slow and not too fast. While precious seconds lost in the early kilometers cannot be made up later, going out too fast can be even more disastrous, burning the contenders out prematurely and ultimately leading to even slower times.

Milde’s team has taken extraordinary care in selecting—and even rehearsing—the pacemakers. The three men who will be pacing the lead group—Kenya’s Sammy Kitwara, Gideon Kipketer and Geoffrey Ronoh—must be nearly as strong as Bekele, Kipchoge and Kipsang, and they are. Kitwara has a marathon personal best of 2:04:48 and an even better half-marathon best of 58:48. Kipketer and Ronoh are nearly as good with 2:05:51/59:43 and 2:10:09/59:45 credentials, respectively.

To help the pacers stay on track, the organizers will use a lead car provided by race sponsor BMW with two different timing displays. The upper display will be larger and will show the traditional running time of the race.  But the lower display will be connected to a laptop computer running an application which will translate the pacers’ current pace to minutes and seconds per kilometer so they can adjust their speed as needed.

Remarkably, the application has been programmed to sample the pacers’ speed every 200 meters for the first two kilometers and will adjust the display output, accordingly. After that, the program will adjust the display’s output from data samples taken every 500 meters through the 30-kilometer mark where the pacemakers are expected to drop out.  The displays will use very bright white numbers which are easily readable even in bright sunlight.

To make sure Kitwara, Kipketer and Ronoh are comfortable with the system, they will practice with it on a closed street in the nearby town of Eichwalde today.  Race organizers briefed the pacing team and their management this morning on how the system will work, and are transporting them to Eichwalde this afternoon.

Just as critical is the pace itself, something upon which Bekele, Kipchoge and Kipsang apparently do not agree. Kipchoge has requested a first-half split of 1:00:45, a pace of 2:53 per kilometer, which would produce a finish time of 2:01:30 assuming a level pace. When asked about this at today’s press conference, Bekele said he didn’t want to go out that fast.

“That’s not my goal; that’s not my plan,” Bekele said before breaking into a nervous smile. He added: “Really, I want to listen to my body during the race, and what’s going on. I don’t want to stress myself.”

Kipsang agreed, saying that 1:01:00 to 1:01:15 was fast enough. Bekele refused to say how fast he planned to go.

Kipchoge’s coach, Patrick Sang, said that he wasn’t worried about the pacemaking. He reminded a group of reporters that Kipchoge had run 2:04:00 at this marathon in 2015 despite having his partially dislodged insoles flapping out of his racing shoes.

“I’m not worried about anything,” Sang told Race Results Weekly matter of factly. “I believe that he’s an athlete with a lot of experience, and I know he’s going to give his best. In 2015 he ran here with the sole coming out with no pacemakers (in the latter stages), and he ran alone. He’s more of a front-runner, so I’m not worried about that.”

Indeed, Kipchoge was the picture of calm today in his all-black NN Running/Nike warm-up suit. The reigning Olympic Marathon said he had recovered fully from his historic 2:00:25performance at the Nike-sponsored Breaking2 exhibition at the Monza race track in Italy last May where he ran the fastest certified-distance marathon in history (the event was not IAAF record-eligible due to the use of rotating pacemakers and other technical factors).

“It’s really good to be back here in Berlin for 2017,” said Kipchoge, who made his intentions clear. “Wining is not an option; it’s a necessity. You know we are three, but only one winner.”