Beating up Rangers brought Celtic Park to a dizzy high and, as it unfolded, you wondered if any of their best stuff can be brought to bear on a bigger stage.
That’s the tantalising thought for Celtic folk, that the work-rate and energy and the slickness of their attack can unleash a new kind of Celtic on Europe.
Their fans have a right to dream. Pre-season brought victories over Chelsea and Manchester City and gave them a momentum that they’ve carried on.
Auston Trusty and Alex Valle are in and bring depth to the defensive options.
Arne Engels is apparently their biggest-ever signing and his presence on the bench seemed to draw out the best in Bernardo, who was strong and influential.
Luke McCowan adds to the midfield. Adam Idah is a fine counter-balance to what Kyogo brings.
This looks a Celtic team, and squad, heading quickly in the right direction.
On Sunday, Rangers were a small speed-bump and nothing more.
Celtic are disappearing over their horizon and they need to somehow remain calm in that reality. Obsessing about what their neighbours are doing, and spending madly in a bid to catch up, has led them down some dark roads in recent years.
The clubs operate in the same eco-system but the gulf is large and, on occasions like Sunday when Celtic are so alive, it can become vast.
As tough a concept as it might be to get the head around, Rangers can’t be Celtic’s barometer. That’s not the measure of their worth.
That examination comes across eight match days between September and January, when Celtic must punch up rather than punch down. The message from Sunday is that they might be ready to give it a rattle.