But, with just one more warm up game before the Hoops face KR Reykjavik in their opening Champions League qualifier, the time to get serious has arrived.
And, making a big challenge for inclusion on Tuesday is Teemu Pukki, whose hat-trick was the highlight of the 5-2 win over LASK Linz in Austria last night.
Even Amido Balde managed to get in on the scoring after the Hoops had seen Liam Henderson sent off.
Leigh Griffiths rounded off an excellent and industrious performance in an advanced right midfield position with the final goal of the night.
With Anthony Stokes having already got off the mark with the opening goal in the first match of the tour, against Krasnodar, the sight of so many strikers hitting the net has delighted Deila, given how attackers notoriously require more time than other players to get up to speed.
Who is selected to start against Dukla Prague on Friday may give some indication of the way Deila is thinking for next week, when the action begins for real.
The Hoops can go into that match with their tails up after last night's victory was added to the draw with Rapid Vienna and the win over Krasnodar.
But, no-one's confidence will be able to match that displayed by the former-misfiring Finn, Pukki.
He got the goal against Rapid after coming off the bench, but took full advantage of a rare start last night to score Celtic's first three goals before leaving the field with 13 minutes of the match still remaining.
His performance offset, at least to some extent, claims that skipper Scott Brown may have to sit out the first three months of the campaign. It has been reported that the results of a scan on the hamstring tear sustained in the opening minute of Sunday's game against Rapid confirmed the worst.
His presence, drive and leadership would be sorely missed as Celtic seek to battle through two qualifying rounds and a play-off and book their place in the Group Stage of the Champions League.
With his loss in mind, Deila wasted no time looking for a replacement at the heart of his team, and Nir Biton provided some succour for the manager robbed of his on-field powerhouse.
Against Linz, the Israeli was pitched in for his first action since the first week of March, when he sustained a thigh and hip injury while playing for his country.
The composure and assurance displayed by Biton belied the length of his absence, but underlined how important he can be for the Hoops in the coming season.
Sure, it was only against a third-tier Austrian side, and his comeback was limited to 45 minutes, as planned.
But if Biton can replicate this form against Dukla on Friday, then, like Pukki, he could find his name pencilled in for the Reykjavik game even before the squad leave Austria to return to Glasgow.
It is a case of opportunity knocks for those brave enough and hungry enough to grab their chance during this series of warm up games.
Which must leave serious question marks hanging over the future of Tony Watt, who, three games in, has yet to set foot on the pitch.
Watt believed that, after being frozen out during his season-long loan with Belgian club Lierse, his return to Celtic Park would herald a fresh start under the new boss.
But again last night he was left to sit and watch Pukki, Balde and Griffiths take their goals and their chance.
Not only that, the striker who made his name by scoring against Barcelona while still only 18 is now having to look on as a clutch of younger players overtake him into Deila's plans for the future.
Last night was their stage, given that Linz are the weakest of the four teams the Hoops will play in this series of warm up games.
The match afforded most of the first-team regulars some welcome and well-earned respite.
The kids had acquitted themselves very well in their cameo appearances to date, and Deila wanted to see what they could bring to the party if given a longer run.
They didn't disappoint. But all of them had to play second fiddle to pumped up Pukki.
His first goal came after he ran onto a clever reverse pass from Griffiths, holding off his marker, then drilling a shot from 18 yards beyond the reach of the Linz keeper, Pavao Pervan.
It brought the Hoops level 12 minutes before the break, having conceded a cheap goal.
From what had been Linz's fourth corner, Radovan Vujanovic bundled an effort in from close range after Stuart Findlay had failed to win the ball cleanly in the air.
The Hoops had already come close to losing a goal from a corner, Adam Matthews - skipper for the night - popping up on the post to hammer a shot clear.
The Welshman's link up play with Griffiths was one of the features of Celtic's first-half performance, and must have impressed Deila.
Likewise, Biton and Henderson formed a decent partnership in the middle of the park, allowing Callum McGregor to burst forward from deep.
With Leo Fasan, Dylan McGeouch and Balde coming on at the break for Zaluska, Biton and Bahrudin Atajic, Deila demanded his side step up a gear.
However, McGeouch's first involvement was a pass-back which found Eoghan O'Connell on his heels, allowing Tobias Pellegrini to run past him and put the ball beyond Fasan before the substitute keeper had even touched the ball in the nine seconds play which had elapsed.
Pukki fired Celtic level again within three minutes, then tapped in to make it 3-2.
Henderson - booked in the first half for a strong tackle - was harshly dismissed after being shown a second yellow card for dissent.
Despite the numerical disadvantage, Celtic finished strongly, and further goals from Balde - after clever and determined play by McGeouch - and Griffiths underlined their superiority.