The group stage draw is next Thursday, with the Parkhead club favourites to be in it after grabbing a 1-1 draw in the first leg of their play-off in Slovenia.
But the Swedish defender refuses to look beyond Tuesday's return tie at Celtic Park - because he believes they have already passed up a great opportunity to hold an even stronger advantage.
Lustig was witheringly honest in his assessment of how poorly Celtic played when they lost 4-1 in Warsaw in the previous away game on the road to the Champions League, but he was delighted there was the required improvement in Maribor.
But Lustig is honest enough to admit they should have hammered home their advantage - converting only one of their 13 attempts on goal - and that they have still left the door ajar for the Slovenian champions.
He said: "Absolutely, we are the favourites to go through. Right now, we have one foot in the Champions League, and we are going to play the second leg back at Celtic Park.
"Hopefully, we can play a better game there. When we went to Maribor, we would have thought 1-1 was a decent result.
"But, with a bit more quality and a bit more luck, I think we could have won the game."
Lustig is at least satisfied that Celtic have proved they learned from their bitter experience against Legia Warsaw.
However, he needs no reminding it required a ruling from Uefa and CAS to let them appear in the play-offs.
And he does not subscribe to the theory they have shown they have the quality to be playing at that level - not yet, anyway.
"I don't know if we proved that on Wednesday," he insisted. "It was a game we should have scored at least three goals. But we didn't do that."
Lustig does accept, however, misfortune played a big part in denying them a healthier lead to take into the second leg, with Virgil van Dijk's goal-bound header which struck Stefan Johansen's face as the midfielder was on the goal-line the low point of their bad luck.
Lustig conceded he had never witnessed anything like that before, but added philosophically: "Things like that happen. But we should have scored more, anyway. And I think we should also have had at least two penalties.
"I thought it was handball when Anthony Stokes had his header blocked, and I was sure we were going to get the decision when Beram Kayal was brought down."
Against a dangerous counter-attacking Maribor side, Lustig knows the Hoops will need to be more clinical in their finishing if they are to be sure of making it though to the group stage.
And, given the fact they looked out after Legia, and went into last season's play-off second leg trailing Shakhter Karagandy by two goals, the Swede is grateful that they are where they are.
"Before the game, we would have taken a score draw to bring back to Glasgow," he said. "It's not a bad result. But we do need to have a bit more quality in their box to win this game."
Lustig will be heartened, therefore, that the Hoops have identified and are set to move for the player Deila believes will bring this to the side.
However, even if they do succeed in signing Stefan Scepovic from Sporting Gijon, the Serbian hitman will not be eligible to play until the group stage.