Roger Federer is one of the few great players left who has a one handed backhand. He can hit it with power and topspin but as you mentioned also can slice it. That's a huge advantage for him on grass. It's also the reason he's the greatest player of all time. It's no coincidence that the two handed backhand has grown in popularity while at the same time the number of grass courts worldwide has fallen off a cliff. Of the men's top 20 only about 6 or 7 play with a one handed backhand, on the women's side I think it's almost extinct.
My prediction for tomorrow is five sets. I will say that Joker does also have an advantage in that the center court now is so beat up it plays more like clay which helps his game.