Looking at last season's game between Chelsea vs Real Madrid I think it's difficult for Real Madrid to win the game.
I'm sure Chelsea will repeat last season by getting rid of Real Madrid again. But if we talk about winning the Champions League this season I doubt that Chelsea will repeat to be Champions again.
It is true that Chelsea eliminated Real Madrid last season and this would be enough for Real Madrid to be very careful against them this time. However Real Madrid are performing way better than Chelsea this season. I mean not only the domestic league but also the Champions League. Real Madrid eliminated a very tough opponent like PSG even though they had a big score disadvantage first. This time could be really different and I believe Tuchel is also aware of this. He must get his players well-prepared for this matchup.