Brendan Rodgers acknowledged that Borussia Monchengladbach had outplayed his side but the manner of the goals lost was still painful for the hoops boss.
Celtic survived the first half without losing a goal thanks to some resolute defending and the form of Craig Gordon.
Apart from a late chance that Scott Sinclair blazed over the bar it was almost one way traffic as Gladbach demonstrated that they were in town to collect full points.
Two mistakes from Kolo Toure, in the 57th and 77th minutes, were seized upon by Gladbach as Celtic’s hopes of European football beyond Christmas slipped away.
After the thrills of the Manchester City match it made for painful viewing but in context it was hardly surprising. Losing to Gladbach will always be less painful than Europa League defeats away to teams like Molde.
“The best team won, there is no argument about that,” Rodgers admitted.
“If you make mistakes at this level you are punished. We were up against a top side and my players gave everything. Both of the goals were disappointing. We gifted them two goals.
“We set out to press them, but if you are not quite at it they can play and pass around you. We were beaten by a fine technical team who were powerful and good on the counter.
“It doesn’t matter how good we can be, we still need elements to be able to compete on a consistent basis.
“We’ve done fantastically well to qualify for the Champions League, but tonight we have to hold our hands up. We have to find a way of being consistent at this level.”
With the gulf between the domestic game and the elite exposed Rodgers must lift his side for Sunday’s BetFred Cup semi-final against Sevco at Hampden.
The first stage of a domestic treble will be very welcome but in the real world the gap between Celtic and the levels of the Champions League look worryingly large.
