Wont be easy at all, Madrid will be super motivated as a loss would essentially mean the end of La Liga for them.
Contrary to what some people believe, there's not a lot between the teams. I think we can get a draw. Madrid need to win, but at the same time, they need to make sure they don't lose, because losing means they're pretty much out from the title fight.
Maybe they will start in attack, but I'm not convinced they will play an all-out-attack kind of game from begining to end. That's not Zidane's style based on what I've seen so far. Many depend on the kind of day Messi's in. Not a popular opinion, but imo he's not as consistent atm. When he's on he's the best there is, but when he's a bit off, he's easier to block or mark out than in the past.
So, we might see a game where Messi shines and we end up wining or drawing at worst, or we can experience a game where Madrid blocks him almost completely and in this scenario we'll find it hard to get something out of the game. I'm prepared for a loss myself. Think Madrid's problems are motivational atm, and we won't see that in a derby of this magnitute, so their extra edge will turn this game in their favor.