De Rossi was dumped by Roma and replaced by Ivan Juric.
Giannini told TMW: "There is little to comment on, it is the destiny of coaches. It is clear that since he was a flag and a point of reference, it is a shame, but it is always the same. Coaches are at the mercy of the clubs and the results, these two are key components of the entire career of a professional.
"Yes, very much so (I was surprised). We're talking about a coach who had renewed his contract a few months ago, sorry."
"I expect a civil protest at the stadium on Sunday and I think it's in the air. I say this above all because of how this removal happened and because I know the environment."
Asked if he felt the players were with De Rossi, he added: "Yes, because otherwise the players would be idiots. I don't think that individuals who play for Roma could have the stupidity to go against a figure like Daniele.
"There can be a comparison, but the player only thinks about playing, I don't think they had the strength to determine the dismissal."