During yesterday's UEFA presser, Giroud admitted the recent events at Chelsea meant he was not able to give Pioli as much inside information on his opponents as the coach would have liked.
"I know the boys, I played with so many of them, but they have changed the manager so I don't really know how they are going to play," Giroud pointed out.
"For this new team they are mid-project and it is just a matter of time until they are back at their best level.
"How the welcome from the [Chelsea] fans will be I have no idea but I hope for a good one, because I spent a nice three-and-a-half years here with trophies and I left on good terms, so let's see."
The 36-year-old made it clear throughout the conference that his thoughts are focused on trying to win the game with the Rossoneri rather than the emotions of a return to his previous club, but he did say he is proud to go to the Bridge with Milan in the Champions League.
"It will be a fantastic atmosphere, an atmosphere worthy of a Champions League game," he said. "We have played in big games so we are ready for it. The pitch is wonderful so I think it is going to be a fantastic game.