The Bhoys boss was disappointed with his side's 4-3 defeat to Dinamo Zagreb.
A 4-3 defeat to the side previously bottom in their group is simply not good enough and Ronny Deila said as much by affirming 'if you score three away from home, you shouldn't be losing.'
There was an element of cluelessness about the Bhoys in Croatia, as Dinamo Zagreb took a 4-2 lead after going into the break 2-2.
The result means Zagreb have finished just two points behind Celtic, which does not make for particularly impressive reading.
But the tie was a dead rubber, after all, and Deila's side would have finished second in the group regardless of the scoreline last night.
And the Norwegian has made an emphatic promise after describing Celtic's performance as 'poor' (rather mildly put).
RD: "It's going to be totally different in the knock out stages and we'll be a much better team than we were tonight." (KM)— Celtic Football Club (@celticfc) December 11, 2014
Celtic fans will certainly hope so. And perhaps another positive to consider is the fact that a 4-3 defeat away from home in the knockout stages would still leave the Hoops in a relatively strong position ahead of the second leg.
For now, though, focus returns to domestic matters, starting with the SPL.