Brendan Rodgers’ men finally found a way past the stubborn Norwegians to secure three vital Europa League points
Leigh Griffiths came off the bench to score a late winner for Celtic in their Europa League Group B opener against old foes Rosenborg at Parkhead.
The Hoops knocked the Norwegian outfit out of the Champions League qualifiers earlier in the season and also in 2017.
That familiarity appeared to contribute to an insipid first 45 minutes which ended with visiting keeper Andre Hansen touching a shot from Odsonne Edouard on to the outside of the post.
The Scottish champions continued their struggle in the second half until the 87th minute when Griffiths, on for Edouard, headed in a Dedryck Boyata knock down for a 1-0 win and three points that had looked like escaping them.
The first half only warmed up towards the interval.
Celtic had lost just once in eight previous meetings with Rosenborg so there was a certain expectancy among the home support, who saw defender Mikael Lustig take over from an ill Kristoffer Ajer.
The visitors looked solid enough in the early stages, their flair coming from Tunisian striker Issam Jebali, who, along with Serbian midfielder Djordje Denic, were new faces in the side from the last visit to Glasgow.
Amid the early skirmishes, though, Jebali was booked by Polish referee Pawel Gil for simulation after he went to ground inside the Celtic penalty area when taking on Lustig.
Minutes later Hoops centre-back Filip Benkovic, making his European debut for the home side, tested Hansen with a header from a Callum McGregor corner before French striker Edouard fired a Tom Rogic pass over the bar from 16 yards.
However, for all the possession, the zip was missing from Celtic’s play.
But in the 42nd minute Hansen made a fine double save, first from Rogic’s left-footed drive from 16 yards before pushing Edouard’s close-range effort from the rebound on to the outside of the post for a corner which came to nothing.
Rogic had another chance when he broke forward in a counter five minutes after the break but with McGregor steaming up in support, the Australia international chose to fire straight at Hansen.
Just before the hour mark Rogic and James Forrest were replaced by Scott Sinclair and Mikey Johnston as Brendan Rodgers tried a speedier route to the opener.
The two substitutes combined in the 62nd minute when Johnston burst into the box and crossed for Sinclair but his volley on the stretch from 12 yards missed the target.
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The Norwegian side were camped at the edge of their own box without hinting that they were looking to win the match.
Celtic pressed but with diminishing belief.
Griffiths, who recently signed a new four-year deal with the Parkhead club, replaced Edouard in the 76th minute before Johnston turned a Kieran Tierney cut-back over the bar.
However, all was well when Griffiths, from right in front of goal and unmarked, headed Boyata’s set-up from a Scott Brown cross past Hansen to secure the points.