The club’s sporting director is retiring and will be replaced by Hugo Viana at the end of the season.
While Guardiola stresses this is not linked to his own future, he admits that Begiristain is hugely important to him.
"A part of me is leaving, I would say," the City boss said to reporters this week.
"A friend of mine, I would say the architect, to create one of the best teams ever from Barcelona at that time and now here.
"A friend of mine and I knew the decision for a long time, for family reasons and personal reasons. I know how grateful he is for this experience here. Personally, he will be missed, but of course he will be missed a lot - for the confidence, for the trust, especially in the bad moments, because he made me incredible balanced in my job because I am so energetic.
"When I am going bad, I want to destroy everything and all the time he said, 'See you tomorrow, take a coffee'. His balance to be completely crazy in the other one, his pulse, helped me a lot in my period in Barcelona and of course here.
"But I have the opinion that the club is so solid, incredibly well-structured and it has to be like that. All the families have to move on and the club will move on."