The Celtic manager has accepted responsibility after his side lost on penalties to arch-rivals Rangers at Hampden Park.
The Bhoys twice came from behind against their arch-rivals at Hampden Park to secure a 1-1 draw after 90 minutes and a 2-2 draw after the extra 30, before suffering heartbreak from the spot.
The defeat is a hugely damaging one for the context of the Hoops' season, and for Deila, whose job has been called into question at numerous times throughout the season.
With speculation suggesting that the Norwegian' future at Parkhead could potentially hinge on whether or not Celtic beat their rivals and went on to win the cup, Deila would be forgiven for looking nervously over his shoulder after the defeat to the Scottish Championship winners.
However, the 40-year-old made no effort to dodge the blame or run from the loss, admitting to BBC Scotland that he is the one who must take the fall.
Deila said: "Overall it is my responsibility. If that is not good enough, then it is not good enough. I'm very disappointed of course. It was draining. You want to win football games and in the end it was not good enough.
"It was a very hard game, but we now have to fight for the league. We have a very good chance but there are still five games left, so we look at it after that. In football, you never know."
Celtic now only have the Scottish Premiership title to add to their trophy cabinet this season, and though they look certain to secure that silverware and a fifth championship in a row, they have been far from convincing at times in their domestic campaign.
Deila and his side have a week to brood over their Old Firm loss before hosting Ross County next Sunday.