I think what a lot of people forgot in the leadup to this match is how well Rafa knows Rublev's game. We all see Rublev as a hotshot up-and-comer but he practices with Rafa a lot and Rafa knows Rublev's game.
Rafa has spent hours looking at Rublev's balls. He knows the type of shots that he hits and there was really no suprise element for Rafa playing Rublev.
So it was only going to be an issue of Rafa executing correctly and being comfortable in the conditions (which were overwhelming but far more adjustment needed for Rublev than Rafa in this regard).
When I looked at the draw I figured if they did play Rafa would win in 4, but after I watched the Rafa vs Dolgopolov match I changed my prediction to straight sets. Rafa really flicked a switch in that match vs Dog.