Brendan Rodgers has warned his defenders that switching off for a split second against Zenit St Petersburg could spell the end of the road for them in Europa League.
Celtic approach the last-32 tie against the Russians still fighting on all fronts but amid pressing concerns as to their vulnerability at the back.
Shorn of Dedryck Boyata through injury, Rodgers is likely to again partner teenager Kristoffer Ajer with Jozo Simunovic despite the latter being twice at fault in the 3-2 Scottish Cup quarter-final victory over Partick Thistle last Saturday.
Brendan Rodgers is preparing his players for defensive solidarity ahead of Thursday’s clash
Facing a significant step up in class, Rodgers has left his Celtic rearguard in no doubt as to their responsibilities – and the likely consequences if they fail to deliver.
‘The manager has been reinforcing to them the concentration aspect,’ said Parkhead No 2 Chris Davies.
‘It’s really important at this level. When you are facing teams like Zenit it can be about that mental fatigue.
‘You need to concentrate, be switched on and alive, for every single moment of the game. That’s going to be very important on Thursday to ensure we are defensively solid.
‘Domestically we are used to having a lot of the ball, then you come in to Europe and you are not the team with most of the ball.
‘It’s something you look at in training and try to help the players. The manager has been reinforcing to the players the important of defensive organisation, concentrating on being hard to beat. We know we have threats going the other way.’
Celtic are used to dominating in Scotland, but that will change against Zenit St Petersburg
As well as Boyata, Rodgers will still be without Patrick Roberts and Stuart Armstrong, with regulars Craig Gordon and Leigh Griffiths also missing.
Despite the postponement of a scheduled development squad game with Motherwell on Monday which would have given him some much-needed game time, Tom Rogic has a chance of making his competitive return at some point.
‘Tom is a little bit further ahead,’ Davies explained. ‘He has a good base of training and was due to play for the development team on Monday to get some minutes.
‘He’s at that phase now that he’s had a good couple of weeks training. So there’s a chance that Tom will be involved in the Zenit games. We’ll just have to see how he is and make a decision.’
Despite again making it through to the group stages of the Champions League, Celtic failed to take a point from their three home games with Paris Saint Germain, Bayern Munich and Anderlecht.
Chris Davies says the players must take advantage of the Parkhead home crowd on Thursday
And Davies acknowledges that, in order for that pattern to change, the team must first give supporters something to feed off.
‘The crowd are fantastic and, as we have said before, there is no better place to play than Celtic Park in Europe,’ he said.
‘The atmosphere they generate is incredible. It’s up to us that it inspires us and it intimidates our opponent. So we have to use the atmosphere.
‘The reputation of Celtic Park will never go away. We’ve got to focus and use that as inspiration.
‘We have to make sure we are concentrating on the game and not thinking too emotionally but tactically, and then it will start to intimidate the opponent.’