Some call it crazy, others call it impossible, but everyone in the long-distance running community is talking about it. Nike, in a project called Breaking2, has issued a moonshot marathon challenge: Break the two-hour barrier.

Early Saturday morning in Monza, Italy, three men -- Kenya's Olympic marathon champion Eliud Kipchoge, Ethiopian Lelisa Desisa and Eritrean Zersenay Tadese -- will test whether Nike's investment in research and development, training, nutrition and in the athletes themselves pays off.

But a funny thing happened on the way to the forum. Or rather, the Autodromo Nazionale Monza, where the men will run. Mary Keitany ran 2 hours, 17 minutes, 1 second in her third London Marathon victory, breaking the women's-only marathon record held by Paula Radcliffe for more than 15 years. (Radcliffe still holds the "mixed-gender" record with a 2:15:25.) And so we must ask: What about women?

"They never talk about the women doing something," Keitany said. "They just talk about the guys, the men."

So how about it?

In addition to Keitany, we spoke to reigning Boston Marathon champion and fellow Kenyan Edna Kiplagat as well as Jordan Hasay, a 25-year-old American who placed third in Boston -- her very first marathon -- and smashed the American-debut record by almost three minutes.

We asked these three women to help chart the next frontier in the women's marathon, to identify a goal time, how to attack it and which runners have the best chance of breaking it.

Warning: There were no simple answers.

Setting the goal

Edna Kiplagat believes it will take a group of women pushing the pace together to break the 2:15 mark. Keith Bedford/The Boston Globe via Getty Images

Forget two hours. That's not going to happen. At least for the time being.

Kiplagat, a 37-year-old two-time world champion, set the clock for women at 2:15.

"If we get more established athletes like Mary and me, or those running 2:19 and 2:18, maybe two or three of them in the same race ... then maybe one of them can break away, and it might be a surprise -- she runs a 2:15," Kiplagat said.

The pack is the key, for a number of reasons. Although marathoners ultimately want to beat their competition, they also have a deep camaraderie unique to such a grueling contest. Unlike almost any other sport, marathoners often work together -- sharing water bottles, training plans, advice, and even the same pace.

"What we need is more people running sub-2:19 in the same race," Hasay said. "It's not really about the time. It's about a pack of women being right there. Then, the record will just come by itself."

Keitany, of course, is going even faster -- it's kind of her thing these days -- and not settling for 2:15. "Maybe sub-2:14. I think 2:13 is possible," she said.

The women worry, though, that the men's mission to break two hours is beyond the limit of the human body. "They will try to make it, but to me it's impossible," Keitany said.

"It's not like a race, it's more like a time trial," Hasay said of the men. "It'll be more important to get into a rhythm, zone out and hold on as long as you can."

Kiplagat is more optimistic. "I think they are going to succeed. They are focused, they have really worked hard for it, and they want to do it. So if they break it, it will show that what other people think is not possible, it's possible."

A big hurdle

Jordan Hasay made her marathon debut in Boston last month and finished in third place in a heartening 2 hours, 23 minutes. Bill Frakes for ESPN)

The top marathoners often focus on winning races more than hitting a goal time. These runners -- competitors -- have an intense and ingrained drive to finish first. It's an inner motivation that demands months of extreme training -- including hundred-mile weeks, thousands of hills, and speed and strength training -- to build up the mental and physical endurance to outkick and outlast the competition.

More than anything, these women aren't out for a good time. They want to win.

"The first thing is winning the race. That's where your name is going to be known all over and the glory comes in," Kiplagat said. "After some time, that's when you can get the confidence to reach a certain goal or time for the next race."

Even in her record-breaking performance, Keitany agrees. "I think firstly, I was going for winning, and secondly, I was going to run under my PB [personal best] of 2:18:37."

Winning a world major marathon not only guarantees a larger paycheck, it also brings more prestige than running a personal best.

Yet even newcomers are ready to see women marathoners go after such an epic time challenge.

"If we put it out there: This is the goal, that gives you an extra level of purpose and motivation to do something spectacular," Hasay said.

The possibility of failure

Part of what makes Keitany so special is she sets aggressive goals and bravely takes the race into her own hands, pushing a pace that can break up a pack in the early miles, often throwing off her competitors' race plans.

But putting that kind of demand on her body requires courage and confidence. Perhaps Keitany's fearlessness is the reason she toppled a marathon record that some thought was unbeatable.

Breaking barriers this big comes with a huge risk. "It's very brave, but when you put [your goal] out there, you set the expectation and you want to deliver. It can be really hard when you don't reach that goal," Hasay said.

And when pushing the limits of human ability in a grueling event like the marathon, there's a chance of not just falling short, but of failing spectacularly.

"If you're going for a win or for a really fast time, there's no way you can get away from that risk," Hasay said. "If you blow up, you blow up. And that certainly is devastating, but you never know when you're going to get that special day when everything comes together."

Where and who?

Of course, our contenders need the right training, and of utmost importance is the right course.

It's got to be flat, it has to be cool -- somewhere between 40 to 60 degrees -- and it has to have adoring crowds. All three women would prefer conditions that replicate a race rather than the closed track setup the men are using. Think Berlin, London, Chicago.

"You never know when you're going to get that special day when everything comes together." Jordan Hasay

How about the who? Hasay immediately mentioned both Kiplagat and Keitany. "In marathoning, I've always looked up to Mary Keitany. So if I had to pick one person, I'd pick her. But then Edna is incredible too. She has tons of experience. She's older, but I wouldn't put her out of the picture."

Kiplagat first picked Keitany, then filled the rest of her roster of dream picks. "Somebody like [Tirunesh] Dibaba. Even Vivian [Cheruiyot], if she started her marathon of 2:23, she still has the chance of improving," Kiplagat said.

At 37, the competitor in Kiplagat still runs strong. "Even for me, I can try. Yes, it's very exciting. I ran a 2:19, and so there's a possibility of improving."

Keitany was more uncertain -- perhaps it's too soon to think about threats to her throne. "I could not tell you who," she said. "It's too tough to call.

Hasay looks forward to taking more risks as she gets more experience as a marathoner. Could she be the one?

"You want to be on the red line, right to that limit," she said. "But that's what I love as an athlete. That's what drives all of us is to be on that line."