BRENDAN Rodgers has overseen some memorable triumphs and been responsible for some fine achievements in the short time which he has been in charge of Celtic.

Champions League qualification has been secured, Rangers thrashed on more than one occasion, an historic fourth treble recorded and an unprecedented unbeaten domestic run completed since he was appointed just last year.

But the Northern Irishman will have to inspire a display to equal or even top anything which has gone before if his side is to avoid an unthinkable early exit from Europe's premier club competition next week and suffer the worst result of his brief tenure.

It was not the fact that Celtic had failed to beat Rosenborg in the first leg of the third qualifying round last night which will be concerning for Rodgers.

No, it will be the paucity of their all-round performance against the Norwegians which will trouble him ahead of the rematch at the Lerkendal Stadium in Trondheim on Wednesday evening. They posed no threat up front and could very easily have lost.

"We were closer to winning the game," said the beaming Rosenborg manager Kare Ingebrigtsen afterwards. "It would have been a better result if the game had finished 1-1. But I am more confident now.

Having Leigh Griffiths available will certainly help the Scottish champions to pull off a memorable result and go through to the play-off. But precious few of their supporters will be confident they can prevail away from home after witnessing this disjointed and flat showing.

Celtic were dealt a huge blow before kick-off when Moussa Dembele failed to pass a late fitness test. Rodgers confirmed the French striker will be out with a hamstring strain until September at the earliest.

Given that the 20-year-old spent the final weeks of last term sidelined with the same injury it should rule out the prospect of the prolific scorer, linked with multi-million pound moves to a plethora of clubs this summer, departing in this transfer window.

But it is a serious setback to his club at this critical stage in the season. His absence was certainly keenly felt last night. With Griffiths suspended it meant that Tom Rogic had to move up front into what his manager had described as a false nine.

The Australian beavered away admirably in a role had been asked to perform on occasion last term. But the home team badly missed the threat posed by Demeble and Griffiths in the final third whenever they are in the field.

Both Stuart Armstrong and Rogic had shots blocked in the visitors’ area early on. But Andre Hansen in the Rosenborg goal was hardly tested.

The Tippeligaen champions, as expected, sat deep when their rivals were in possession, as they were for the majority of proceedings, and had Anders Konradsen positioned just in front of a four man defence and a four man three quarter line not far ahead of him. They proved difficult to break down.

Not having a specialist striker who could hold the ball up or stretch the rearguard undoubtedly counted against Celtic.

Rogic got in a position to get a shot away on the edge of the Rosenborg penalty box five minutes into the second half. But he hesitated and was quickly dispossessed by Mike Jensen. It wasn't his finest performance. He was, however, not alone in that.

The whole Celtic team looked decidedly uncomfortable with the new set-up. Mikael Lustig performed brightly at right back to begin with. New signing Oliver Ntcham also made some nice touches in the in the centre of the park early on. Scott Brown broke down opposition play and sprayed the ball about precisely. But few others impressed.

Stuart Armstrong, James Forrest Scott Sinclair and Kieran Tierney, four of the stalwarts of their treble winning season, were all way below their usual high standards.

The absence of both Dedryck Boytata and Erik Sviatvchenko due to injury led to Kristoffer Ajer, aged just 19 and with little more than half an hour of first team football for Celtic behind him, being handed his first competitive start at centre half.

Coming on in the Champions League second qualifying round match against Gibraltarian minnows Lincoln Red Imps last season was little preparation for a game of such importance. Especially considering he found himself up against his revered countryman Nicklas Bentdner.

But the 6ft 5in defender, who slotted in alongside Jozo Simunovic in the heart of the Celtic backline, impressed during a loan spell at Kilmarnock last season and he showed why here. He looked unfazed by his sudden promotion and received a booking for a robust challenge on Elbasan Rashani

Ingebrigtsen’s charges tried to grab a precious away goal whenever play allowed. In the second half they grew in confidence and tested their hosts on a few occasions. De Lanlay forced Craig Gordon to tip his free-kick over the crossbar, Jensen tested the keeper with a long-range drive and Bendtner had an tame effort saved.

De Lanlay, the Norway winger, fired over the crossbar after an error by Brown and Bendtner snatched at a Jensen cut back with the goal beckoning invitingly. Rosenborg had the better of the second half and could easily have triumphed had they showed more composure in attack.

Rodgers put on Jonny Hayes for Ntcham and replaced Forrest with Kundai Benyu. But the replacements made little difference.

Armstrong tried his luck from outside the box and went close and Hayes did well to tee up Tierney with a shot in the closing stages. But the Scottish champions looked more likely to concede than score. Gordon denied Rahsani with his legs in injury-time.

Having Griffiths back will be a huge positive. But Celtic provided little evidence here they will be able to pull off a famous away win and progress to the play-off.

Making it through to the knockout rounds of Europe's premier club competition was seen as the next logical step for Rodgers' side by many after last season. But even salvaging a Europa League spot would be an accomplishment after this.