The police message matters because this derby is always played under a microscope. When emotions run high, every flashpoint gets amplified, and the absence of travelling supporters could cut both ways.
That backdrop should sharpen the focus on control. In cup football, especially in a one-off quarter-final, composure can decide as much as quality.
The tactical battle is still the headline. Rangers will look to use the energy of Ibrox and turn the game into a high-tempo contest. Celtic, by contrast, usually thrive when they can impose rhythm, keep the ball moving and force mistakes.
The latest update says Celtic have opened their league campaign with six straight wins, which underlines the confidence they appear to bring into this tie. That kind of form does not win a derby on its own, but it does shape belief.
One notable line from the build-up is that Mika Baur is reportedly available for Celtic despite missing training. If that proves to be the case, it gives Celtic another option at a time when squad depth can swing a knockout game.
The winner will move a step closer to silverware, but the bigger story may be how this derby is handled as much as how it is played. At Ibrox, the next chapter in this rivalry now comes with football pressure and crowd scrutiny wrapped together.