Novak Djokovic and Pepe Imaz are good friends and they “share a partnership.”
Here a video about one of their public sessions. For most of the people, this is tough to watch, from some others it’s enlightening.
The “appearance” of Pepe Imaz usually coincides with Djokovic’s tennis going south, and in the past, Nole’s coaching team was fired (or resigned) for refusing to side with Imaz.
Here the video
https://www.youtube.com/watch?v=JchMDo8oq8Q