At the start of the F1 summer break, Alonso made a bombshell switch to join Aston Martin from midfield rivals Alpine on a multi-year deal from the F1 2023 season, replacing the retiring Sebastian Vettel.
The two-time world champion can be divisive and has been known to demand a lot from his teams in the past, sometimes resulting in a complete breakdown in relationship.
Krack acknowledges that managing Alonso and his expectations will be a challenge for Aston Martin.
"It will be challenging for us,” Krack told BBC Sport.
“Normally, drivers with this experience, they do not have this desire to win. Normally, this desire goes down, especially if they have won already.
"Fernando has this unique combination of speed, hunger, motivation and experience. For us, it makes the perfect candidate.
"The downside could be that if the car we deliver is just not good enough, then we know it gets difficult. But it gets difficult with every driver if the car is not fast enough.
"We think having someone like Fernando is really, really important to make the next step as a team.
"You need to learn to manage champions, which we already did with Sebastian. Because these drivers are very demanding, they are quite difficult to manage. I would not even say Sebastian is that difficult to manage if you are transparent, honest and straight. And I think the same goes for Fernando.
"Difficulties arise when expectation does not match deliverables, or when it's not outspoken.
"He knows very well when he comes here that we will probably not win the first race together.
"But he can be assured we give it everything and we will listen to what he has to say. And if we cannot deliver on something we have to tell him, open and transparently: 'Look, this we cannot do. With all possibilities, this is what we can do next.’
"I think if we have this kind of dialogue, it is not going to be problematic.”
41-year-old Alonso, a winner of 32-grand prix, is still considered one of the best F1 drivers on the grid.
"He can push us, more than a driver who does not have that calibre,” Krack added. “It will maybe be much more difficult than it is now.
"We discussed this. We said: 'What are the pros and cons?' And we came to the conclusion that it is the right step."