Neil Lennon declared it "very difficult" for Celtic to haul themselves back into the Scottish Premiership title race after a 1-1 home draw with St Johnstone - but insisted he would keep fighting to revive their fortunes.
Rangers moved 13 points clear on Sunday after a 4-0 away win over Ross County, who had knocked Celtic out of the Betfred Cup at Parkhead seven days earlier.
Lennon retains the support of the Celtic board after last week's backing from the club and he is expected to be in charge for Thursday's home game with Lille in the Europa League.
However, Celtic have now won just twice in 12 matches in all competitions and only once in five league games to leave hopes of a 10th consecutive league crown hanging by a thread.
When asked if he doubted he could turn their form around, Lennon said: "No, I don't doubt it, I know these players.
"There is definitely a lack of confidence there, a lack of confidence in themselves as individuals and each other. We need to get that back because they can play, they proved that last season.
"But this season it's been a struggle for them. Whether it's a lack of attitude or desire... there's bits and pieces that I see now and again that I can't really change overnight, but I want to.
"As far as the season goes we are making it very, very difficult for ourselves to get back into it.
"I have got to be realistic. I wouldn't say it's over but we are making it more and more difficult for ourselves and we need to start winning games and winning them well."
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'If there's a change, so be it - but I'll keep working'
The cup loss against County sparked angry protests outside Celtic Park but Lennon retained the backing of the club's power-brokers.
After conceding four goals and a two-goal lead against AC Milan on Thursday, Celtic had to come from behind against Saints as Mohamed Elyounoussi cancelled out Chris Kane's opener.
With fans gathering outside Celtic Park again, Lennon said: "I understand their frustrations. We are not playing well, we are not getting the results we should be getting.
"There's ways and means and some fans are more irate than others but at the minute I would agree with them that the performances don't merit the quality that we have.
"If that's on me, then so be it. If there is going to be a change, then so be it, but I will not stop working to try and get it right."
When asked whether the latest setback might change the views of the board and major shareholder Dermot Desmond, Lennon said: "I can't answer that and I don't want to pre-empt anything. I want to keep working and turn it round.
"We need a bit of swagger back in the team which is missing right now. Some players aren't fit enough and that's been the case for a long time. Some players are just not in good form.
"They need some respite at some stage and they need some support from me, but it's a two-way thing. The players have got to play better. We are trying everything we can to get those performances right."