Neil Lennon vowed to ring the changes after criticising his team's character in the second half of their 3-2 defeat by Ross County.
Celtic were two up inside 21 minutes in Dingwall after County goalkeeper Michael Fraser let in soft goals from Charlie Mulgrew, direct from a corner, and Gary Hooper's chip towards the back post.
But County immediately fought back and were level 15 minutes later thanks to Grant Munro's wonderful volley and Sam Morrow's close-range finish after Celtic had failed to clear an Iain Vigurs cross.
Fraser saved well from Miku in between Celtic's goals and Anthony Stokes missed a good chance with the last kick of the first half, and County then had an escape when Fraser parried Hooper's shot against Mihael Kovacevic and off the crossbar.
But County finished the stronger team and Steffen Wohlfarth had already missed a good chance before heading home in injury time after centre-back Kelvin Wilson and goalkeeper Fraser Forster both left Evangelos Ikonomou's hopeful long ball to each other.
Victor Wanyama, Emilio Izaguirre, Adam Matthews and Georgios Samaras had all picked up injuries in Wednesday's Champions League defeat by Juventus in Turin while James Forrest was also absent, but Lennon admitted there was no excuse for his team's capitulation.
Lennon, whose side remain 15 points clear despite consecutive Clydesdale Bank Premier League defeats, said: "I knew it was going to be tough when we came here looking at the pitch and conditions. But we started brightly and you have got to take your chances.
"It should have been 4-2 at half-time, we had clear-cut chances, which on a pitch like this is difficult to do. And the game became a fight in the second half, which you expect it to.
"We lacked men in some areas. And I'm going to have to get some men in."
Lennon, whose team host Aberdeen on Saturday, added: "I'll make changes. I will hopefully have Samaras and Izaguirre back next week, we will see how Victor is.
"It gives us a week to recuperate. We have had a long week. We had a four-hour drive on Friday after coming back from Italy on Thursday.
"So there were mitigating circumstances for a bit of lethargy but what you can't lack is character and I thought we lacked that in a lot of departments. I'm pretty angry about that."
While few if any would have given County hope after 21 minutes, their victory affirmed their position as the SPL's form team of 2013.
If the league had started on January 1, Ross County would be two points clear of Celtic with 24 from 10 games.
Derek Adams' men have now gone 11 games unbeaten since losing at Celtic Park on December 22 and have won five matches out of six to move third in the table.
Munro feels they are reaping the rewards for hard work and belief.
"We work hard Monday to Friday," the defender told BBC ALBA.
"We keep going to the end and I think the fitness showed. We don't give in and we are getting rewards in the final 10 minutes."
The 32-year-old added: "It's unbelievable. To go 2-0 down against any team, let alone Celtic, it's a remarkable achievement to come back.
"I think we got what we deserved and didn't let our heads go down.
"It was great character from the boys. We have a lot of fight in this team and we showed that.
"Going 2-0 down against Celtic you are looking at four or five-nil. But we believed and it shows that if you keep going you get results.
"We knuckled down and got a five-minute spell to try to get back in the game and thankfully one fell to my left foot. I do it all the time in training, so I wasn't very surprised to see it go in.
"But, we got the rewards and big Steffen was very brave at the end."