The Bhoys failed to win against Dundee at home, playing out a goalless draw in the Scottish Premiership encounter.
Deila has said that his team’s performance at Celtic Park was poor, and has admitted that he is disappointed.
"I am very, very disappointed,” the Norwegian told BBC Sport (22:30). “It was a poor performance from start to finish, as a team, not individuals, all over the pitch.
“We looked slow and always a metre too late, which is disappointing. It is about confidence and getting energy back. Today it seemed like they had flat batteries.”
Over the course of the 90 minutes at Celtic Park, hosts Celtic had 58% of the possession, took 11 shots of which four were on target, and earned five corners.
Visitors Dundee had 42% of the possession, took seven shots of which just one was on target, and earned nine corners.
Celtic are at the top of the Scottish Premiership table at the moment with 63 points from 28 matches, just four points clear of second-placed Aberdeen.
The Hoops will return to action on Sunday evening when they take on Greenock Morton at Celtic Park in the quarter-finals of the Scottish Cup.