Deila: I'm to blame for lack of thrills at Celtic Park
Celtic 0-0 Dundee
Ronny Deila took full responsibility after a lacklustre display by Celtic saw their lead at the top of the Ladbrokes Premiership cut to four points following a goalless draw with Dundee at Parkhead.
It was a lifeless performance by the Hoops and had defender Kostadin Gadzhalov not missed a sitter late in the game, the Taysiders would have left with all three points as the Celtic fans booed their side off at the end.
With Aberdeen beating Dundee United 1-0 at Tannadice, the title race is back on. It was a result that cranked up the pressure on Deila with Northern Ireland boss Michael O'Neill tipped as a frontrunner to succeed the Norwegian in the Hoops hotseat once Euro 2016 is over.
Deila admitted: "I am very, very disappointed. 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. It seemed like they had flat batteries."
He continued: "It's my responsibility; we need to lift everybody as a group. The performance wasn't good enough and everyone in the dressing room understands that.
"We need to get back on track again on Sunday (against Morton in the Scottish Cup). We need to perform as well as we can."
Skipper Scott Brown confessed Celtic must do much better.
"We didn't play as well as we could have and I think we have let everyone down, it wasn't good enough. We didn't do ourselves justice," he said.
"Points mean so much to us and we've got one point and it's not good enough for this team.
"We should be making this place a fortress like it used to be but it hasn't been in recent months.
"That's a few games we have let ourselves down in now. It has been long balls and we've not been creating too many chances and it's not good enough overall.
"I am frustrated and they are frustrated and I think everyone at the club is frustrated that we are not doing as well as we possibly can."
With one eye on the William Hill Scottish Cup quarter-final tie with Rangers at Ibrox on Saturday, Dens Park boss Paul Hartley started with skipper Gary Harkins, top scorer Kane Hemmings and Greg Stewart on the bench, although all three came on later in the game to try to nick the three points.
Hartley said: "It was a great team performance. We changed the shape of the team and the personnel and the game plan worked.
"We only had one day to work on a back three but we had a real go at Celtic.
"We didn't let them play from the back and played a high pressing game against them.
"In the second-half I felt we were the better team and thought we could have nicked it and I felt in the last period of the game we looked the more threatening team.
"Overall I am really pleased. We changed the team and people were a little bit surprised but I've got real trust in my players.
"I was always encouraged because of what they've been like since the turn of the year. We've had one defeat against Aberdeen, so with this group anything is possible."
CELTIC: Gordon, Lustig (Commons, 81 mins), Boyata, Sviatchenko, Tierney, Brown, Mulgrew, Roberts, Rogic (Kazim-Richards, 61 mins), Armstrong (Forrest, 46 mins), Griffiths. Unused subs: Ambrose, Allan, Bailly, McGregor.
Dundee: Bain, McGinn, Etxabeguren Leanizbarrutia, Gadzhalov, Holt, Kerr, Low (Harkins, 70 mins), McGowan, Ross, Wighton (Stewart, 76 mins), Loy (Hemmings, 68 mins). Unused subs: Meggatt, Mitchell, Arturo, Andrew Black.
Match rating: 4/10.
Man of the match: Scott Bain
Referee: John Beaton