Pioli switched to 3-5-2 for the Milan derby to mirror Inter last week and he failed miserably. They didn't get a single shot on target the whole game. Inter dominated the first half, got only one goal, but they slowed down in the second and just managed the lead without any big trouble. Yesterday I didn't watch the game but seems like Milan played 3-4-2-1 and there were rumours they'll continue to play 3-5-2 or some hybrid of it at least for a few more games. So I wouldn't be surprised if they play 3-5-2 on Tuesday. They are in a terrible form, I think worse even than Spurs and Conte knows Milan well.
Still, it's the Champions League and it's unpredictable. Will be hard not to watch PSG-Bayern instead tbh but I'll be switching channels from time to time for sure.