Walter Smith says Rangers only had themselves to blame as they slumped to a 2-0 Old Firm derby defeat at Ibrox.
Georgios Samaras was the hero for Celtic after his double secured a 2-0 win as the Hoops moved four points clear at the top of the table, although the Scottish champions do have two games in hand.
The New Year showdown had failed to live up to its billing until Samaras' second-half opener sparked the game into life, and he then sealed the victory from the penalty spot.
As far as Smith is concerned, the nature of those goals was the hardest part to take.
"We've got to be disappointed with the way we conceded the goals," he said. "They were poor goals from our own point of view.
"We've got nobody to blame but ourselves in that respect. I'm disappointed that we lost in the manner we did. If Celtic had scored a couple of good ones, it might have been easier for us to take."
He added: "I didn't think there was a flatness about Rangers today. I thought we played very well up until about 25 yards from goal.
"I think you've got to give credit to the opposition at times. I felt Celtic defended very well today. They set their stall out to play deep and not allow us great opportunity to get behind them. That worked very well for them.
"My disappointment is that we didn't do enough to cause them a problem in that respect. If you were looking at the game, I thought we started that game as well as any Old Firm game I've been involved in."
Neil Lennon revealed a chat with former Celtic boss Gordon Strachan confirmed his inspired decision to play two-goal hero Samaras in the lone striker role.
"I am very proud of the players and performance," Lennon said. "I didn't think there was one failure there today. We were very resilient, we dominated and I thought Samaras was unplayable.
"I spoke to Gordon about that lone-striker's role. Samaras can do that and it was something we have been working on. I have seen him play in World Cups and do that and we felt we would leave him up there to do it.
"He pulls himself off the two centre halves which isn't an easy thing to do. His movement and composure for the first goal was great and although he got a lot of confidence from the way he started the game, he got a huge lift from the goal."
Samaras is out of contract at the season but Lennon is looking for the striker to extend his deal at Parkhead.
"We know he has fantastic attributes - we just need to find that consistency and maybe that role suits him best - but I think he has done himself no harm today regarding a new contract," he said.
Samaras admitted he would be happy to accept a new deal from Celtic - and continue as lone striker.
He said: "I want to stay. If the manager has said he wants me to stay then hopefully in the next couple of days or weeks, we will find a solution and keep going together.
"That is my position, the one I like to play, and it was a nice feeling to score my first goal at Ibrox. My team-mates and me worked really hard and in the second half we were much better than Rangers and deserved to win the game."
Lennon hit back at critics who claim he had yet to win a big game since taking over from Tony Mowbray as Celtic boss last March, first on an interim basis.
"I think it's a huge result," he said. "I think the majority of people in this room, from what I've heard in the last week or so, had written us off and given us no chance.
"The players answered a lot of questions and I think I have answered a lot of questions. People pointed the finger that we don't win big games
"It was fair comment because we hadn't done ourselves justice in those games but we certainly did today. We did with a bit of style was well and I really enjoyed watching them play today, so I hope it's a turning point for the players."