On the line is £15million, a cheque which can underpin Celtic's entire season.
Conversely, failure to grasp this second chance to be included in the Champions League group stage would deliver a serious blow to the reputation of the club – and to the speed Deila can make the changes he believes the club needs.
The Norwegian wants a controlled performance, and will set up in a pressing formation to try and score the goal which would settle nerves.
However, Deila is only too aware allowing Maribor to score first would set those same nerves jangling.
So it’s highly unlikely to be as open a game as the first leg, when both sides had chances aplenty to score.
“We have a plan,” said Deila. “I’m ready, and I know the team is ready, as well. We have everything to win.
“It’s important to start well, to get the crowd with you and show we are offensive in our heads. But you have to be clever and play tactically well.”
Deila was speaking as Henrik Larsson revealed he turned down the chance to succeed Neil Lennon as Celtic manager, opting to stay with Swedish club Falkenbergs.
The Hoops icon said: “Yes, I declined the Celtic job. This was something I had to think about. In the end I chose to remain at Falkenbergs.”
Larsson added there was no agreement in place to become Hoops boss in the future.
Meanwhile, Celtic hope to grab a pre- Champions League play-off boost today by completing the signing of Stefan Scepovic from Sporting Gijon for a fee reported to be around £3million.
The striker’s representatives are now locked in talks over personal terms on a contract expected to be for four years.
The Serbian will become the first purchase by Deila, who believes he can bring the physical presence he wants at the point of his attack.
Unless there are any last-minute hitches, Scepovic is expected to be in contention to make his debut in Sunday’s SPFL game at Dens Park.
As Scepovic comes in, reports in Portugal claim Amido Balde is on his way back on loan to Vitoria Guimaraes.
Celtic also hope to finally complete the paperwork to bring Wakaso Mubarak in on loan from Rubin Kazan, while reports in Poland claim they are trying to hijack striker Lukasz Teodorczyk’s move from Lech Poznan to Dynamo Kiev.