Ronny Deila admits he will have to rebuild the confidence of "sad" Efe Ambrose following his Europa League nightmare against Fenerbahce on Thursday night.
The Hoops were cruising in their Group A game against the Turkish side through goals from Leigh Griffiths and Kris Commons until the Nigeria defender was woefully short with a back header two minutes before the break, allowing substitute Fernandao to pull a goal back and turn the match on its head.
The Brazilian striker then escaped the attention of the 26-year-old former Ashdod player to head in the equaliser from a corner three minutes after the restart, with the home side having to settle for a draw.
Ambrose is suspended for the trip to Hamilton in the Ladbrokes Premiership tomorrow, which the Norwegian boss described as "the worst thing he needs".
Deila said: "Everybody understands that he made a mistake for the first goal, but we are a team and we have to build him up again because he is, of course, very, very sad that he made that mistake.
"He was very down but he sees that he has improved a lot and feels that he is in good shape.
"For 98 per cent of the game he played well, but as a central defender and goalkeeper you are vulnerable for mistakes and if you make one it costs you points.
"You can't do anything else than work hard in training to be concentrated in every match, try to improve what you do in matches and he has improved.
"We know and he knows the issues that he has to work on and we are working on them every day.
"As I said 98 per cent of what he did was good, but of course you remember the two per cent that wasn't at the level you want.
"You have to get back again and play a good full match again.
"He wants to play football again. He will be with the Nigeria team and will come back after that and be ready to play for Celtic."
Deila is hoping that Griffiths, who scored his 11th goal of the season against Fenerbahce, will learn from the suspended two-match ban and £2,500 fine he was given for singing an offensive 'refugee' song about former Hearts player Rudi Skacel.
The 25-year-old was admonished by a sheriff after admitting in court his part in the incident, which took place in a pub before a Hearts versus Hibernian derby at Tynecastle in March 2014.
A Scottish FA disciplinary tribunal found that Griffiths was guilty of "not acting in the best interests of association football" and imposed a punishment described by Deila as "fair".
Deila added: "He now needs to be disciplined and keep out of trouble."