Toni, speaking after Bayern's 3-0 win, said: "It will be an emotional moment in a stadium where I had two fantastic years. It's a crunch match for the group, too.
"Obviously Bayern is my first focus, but I do hope Fiorentina can qualify for the next phase. There is a long way to go and so many points still up for grabs."
Toni left the Viola last year and his first encounter as an opponent saw Bayern win 3-0 in the Champions League.
"The important thing was to put in a good performance and we did that. We scored three goals and created chances, although we ran a few risks too.
"I expected some jeers, that is natural, but some of the chants were a little hurtful. We'll see and prepare for the second leg in Florence."