The Scottish Premiership side go into the second-leg a goal behind.
Celtic manager Brendan Rodgers
Lisbon Lion Bertie Auld has outlined just how embarrassing Celtic's defeat to Lincoln Red Imps in the first-leg of their Champions League second qualifying round tie was by insisting that even a five-goal win in the rematch will not spare the Hoops' blushes, The Scottish Sun reports.
Brendan Rodgers' men were understandably expected to put one foot in the next round by securing a massive win in Gibraltar.
However, they fell to a stunning 1-0 defeat that some are suggesting may be the worst in the club's history, given the stature of the opposition they were going up against.
And Auld has done little to dampen that suggestion by insisting that the scars will remain regardless of how they get on in the home leg.
"I've no doubt that Celtic will score four or five against Lincoln Red Imps at Parkhead but that won't take away the embarrassment of the result," he told The Scottish Sun.
"We've had heavier European defeats but they were all against better teams.
"They deserved their win and I couldn't help but admire them for the way they went about their job. Lincoln were first to every loose ball and won every 50-50 challenge."
With the optimism that engulfed Parkhead following Rodgers' appointment, the defeat may actually prove to be an important moment in the Northern Irishman's tenure.
Anyone who felt certain that Rodgers' arrival would see the Bhoys go far in Europe will now realise that he is not necessarily going to lead the side to overnight success in the competition, while Rodgers may now have a better idea of the areas he needs to work on before they come up against much stronger opposition.