Neil Lennon says a half-time dressing-down inspired his players to come from two behind to seal a dramatic 3-3 draw with Motherwell at Fir Park.
The Scottish Premiership champions trailed 2-1 at the break after they fell behind to goals from John Sutton and Zane Francis-Angol.
Kris Commons missed a penalty before Anthony Stokes pulled one back for Celtic in first half stoppage time.
However, following a heated team talk at the interval the Hoops came out fired up and soon found themselves level when Georgios Samaras prodded home in the 56th minute.
Leigh Griffiths came off the bench to fire Celtic in front in the 86th minute to complete a remarkable turn-around.
It looked as if Motherwell were heading for defeat before Sutton slid home his second to seal a point for his side.
"Our first half performance was poor. It looked as if some of the players were on holiday already so obviously I had a few words at half-time," an angry Lennon, whose side clinched their third title in a row last month, said.
"What was said is between me and the players but obviously they could tell I wasn't happy. We sent them out early as a few of them were just going through the motions and that's not what I expect from a team.
"Even though psychologically the league is won, we are here with an obligation to the supporters who have come here and I think I got the exact response I was looking for."
The Celtic manager also laid into his defence after Motherwell became the only team other than Barcelona and AC Milan to score three past the Hoops this season.
"The first goal was poor. It was a straight ball over the top with no cover and I thought (goalkeeper) Fraser Forster should have saved it," Lennon said.
"The second goal we missed the flight of the ball from a cross and we've not defended it properly. We've gifted them two goals really and Motherwell didn't really have to work for them.
"The second half was more like us and a lot better. We had great attacking intent, good quality and good goals."
Motherwell manager Stuart McCall was proud of his side's performance, that keeps them just three points behind Aberdeen in the hunt for second place.
"I think it was a deserved point and a fantastic game," McCall said.
"It's only AC Milan and Barcelona who have scored three against Celtic this season so to get three goals against them was great and we had a couple of other wee chances with another cleared off the line.
"It would have been nice to have gone in at half-time 2-0 but it was a great goal from Stokes. When you are 2-0 up and lose a goal right on half-time and they score so early in the second half you think it is just a matter of time.
"They came on strong but we stuck in there and then I thought we started playing our better football.
"Losing a goal with three minutes to go was heart-breaking for the lads because they put so much into it but what character from the lads to bounce back."