This is already an interesting test for Sarri. I think it's risky to rely on the same gameplan that requires so much from Pjanic if he's compromised. You are really asking a lot from him to play through whatever knock he has against such a sharp side.
Do you just play Bentancur and adjust your style so there is much less build up in your own 3rd? Perhaps longer balls. Maybe the game is not so "beautiful" and you are relying more on a counter press to win the 2nd balls in Atletico's half.
I understand it takes time to adapt the whole style of the team but maybe just take a break for one match and be more pragmatic lol. I really, really, really hope we can see some ingenuity in this match. I think it's a big test. It would be a huge letdown to just go against Atletico and try the same stuff that didn't look great against Fiorentina, and get smashed.