Stefanos Tsitsipas hasn't had much success against Novak Djokovic over the years and it certainly increased his respect for the Serbian and what he did in tennis.
Tsitsipas is a very hard worker who is dedicated to his craft and it makes him appreciative of greatness when he sees it. There is plenty of that with Djokovic and he heaped praise on him in a recent talk saying that he is a perfectionist that took tennis to another kind of level:
“He is the toughest and the most consistent. A perfectionist who took tennis to another kind of level. His diet, his physical work, the stretching, and his professionalism in every single area. I don’t think there is a single thing that he hasn’t thought of. Even the analysis I’ve heard from him. Novak is very advanced."