Everyone knows just how much qualification to the group stage of the competitions is worth to the Parkhead club and probably more so this season than previous years because of the loss of Old Firm matches.
When it was announced Rangers would be playing in the Third Division this season, the Celtic manager admitted the change in circumstances and life without their biggest rivals could force him to sell a player to help balance the books.
But if he can lead his team into the group stage of the Champions League then he would ensure somewhere in the region of £10m-£15m coming in and you would like to think some of that money would be invested in the playing squad.
The big call is whether you spend in an attempt to enhance your chances of qualifying or whether you increase the chances of not qualifying by waiting until you know for certain you are in the group stage before splashing the case.
That is a decision only the chief executive Peter Lawwell and Neil Lennon can make. I'm sure Neil would rather take the gamble and sign someone to play in the qualifying matches, but the financial situation might make that too big a risk to take.
Supporters often talk about speculating to accumulate and I understand what they mean by that because going out and signing a new defender or a new striker might be the difference between beating Finnish champions HJK Helsinki and whoever they'd then face in a play-off match.
What happens though if they do spend big money on a new signing and miss out? It would put a big dent in the club's finances.
I still believe, regardless of whether Celtic qualify or not, one or two players will leave. Neil will be keen to freshen up his squad and the likes of Ki has been linked with a move away from the club for a while.
He has already managed to get a few bodies off the wage bill but the next task is to try and bring in some decent money by selling someone. As I've said, Ki would make the most sense due to the fact there are quite a number of options in midfield.
What might happen, though, is someone could come in for the likes of Gary Hooper. There has been speculation in the past Southampton want to sign him and that really could leave Neil with a big decision to make.
If they weren't to make it into the group stage of the Champions League then he might be left with no option but to accept it.
So when you weigh up all these factors, you realise how important these qualifying matches are.
Helsinki have the benefit of being in the middle of their domestic season and that is sometimes the problem Scottish clubs face.
Celtic's first competitive match will be against a team who are something like 17 games into their domestic league campaign.
And that's why Helsinki will feel they've got a chance of causing an upset. It has happened in the past and it really is tough to make sure your players hit the ground running in only their first competitive game.
There is no room for error. If you draw or lose your first league game, there is more than enough time to make amends. That isn't the case here. Celtic need to play well on the night and get a positive result at Celtic Park on Wednesday.
Would I be comfortable going over there with a one-goal lead? Not really. I'd much rather Celtic are two or three ahead and it means they can relax and if they lose a goal then it isn't the end of the world.
But this is a game they've got to try and take control of from the first whistle and dictate play with a view to scoring a few goals. For me, Celtic should have more than enough quality to win the two legs.
Neil will have to decide on what his best team is and sent them out to be positive but at the same time be respectful to what conceding an away goal would do to their chances.
I'd think he'll go with four at the back, four in midfield and possibly Hooper and Georgios Samaras in attack. James Forrest is fit again and he provides good pace and creatively down the right flank.
If they can win the first match, it might just allow Neil to go out and get someone to help them in the play-off match which is also over two legs.