The Bhoys lost to Old Firm rivals Rangers in the semi-finals of the Scottish Cup at Hampden Park in Glasgow.
The game finished 2-2 after extra time, and the Gers won the contest 5-4 on penalties.
Deila has admitted his disappointment at Celtic’s defeat, and has explained why his side failed to win.
"I'm very disappointed of course,” the Norwegian told BBC Sport (15:05). “We were too passive in our pressure but started well in the second half. We need to be safer on the ball and want to play the ball more.
“It was a hard game and we now have to fight for the league, with five games left. Then we look after that. In football, you never know…”
Celtic should be able to win the Scottish Premiership title this season, but the defeat to Rangers will be a huge disappointment to the Bhoys.
Deila has already come under pressure this season, and failure to progress to the final of the Scottish Cup is going to increase it even more.
The Norwegian is a good manager, but he is struggling to meet the expectations of the Celtic fans.
The Hoops will return to action next weekend when they take on Ross County at Celtic Park in the Scottish Premiership.