Wawrinka was impressive against Lopez. Feli hardly got any purchase on Stan's serve until right at the death and Stan was volleying as well as I've seen him.
This is a tough assignment for Fed, make no bones about it.
The pressure mounts for Roger now that Murray fell. Rafa and Murray are the 2 players you'd definitely/might favor over him in a match. He loses to Stan here then I think it is end of the road and indicates there is no more good tennis left in him on the main stage.
This is where Roger might miss having a testy match earlier in the draw. Huge leap in game here. He's down 3-1, but he can be expected to find his range. It could be that this is the tough match that prepares him for the rest of it...