The Celtic boss was talking to reporters after the 2-1 loss.
If the Dons are to provide a greater title threat to the Bhoys this season, this was certainly a statement of intent.
A notable absentee during the game, meanwhile, was new centre-back Jozo Simunovic.
And Deila has explained that it was simply too early to include the defender in the Celtic first team.
RD on absence of Jozo Simunovic:"Only trained one-and-a-half days with the team so it was too early." (MH— Celtic Football Club (@celticfc) September 12, 2015
In terms of the game itself, however, the Norwegian was disappointed with his side's defending from set-pieces - which has been a common theme for Celtic in recent times.
Next up for Celtic are Ajax in Europe but they will have to produce a better display against the Eredivisie giants than they did at Aberdeen.
RD: "We conceded a lot of goals now from set-plays, something we have to work harder on. It is very frustrating." (MH)— Celtic Football Club (@celticfc) September 12, 2015
It's been a frustrating few weeks indeed for Celtic fans, with Champions League failure then seeing Virgil van Dijk depart on Deadline Day.
Scotland's recent defeats have also been disappointing for many of the Bhoys' Scottish contingent. And now the Aberdeen loss.
But the Europa League is back soon and Deila's men need to grasp their chance in Europe, rebuilding momentum from there.