Callum McGregor scored the only goal of the game against KR Reykjavik on Tuesday night to hand new manager Ronny Deila his first win in the Celtic job.

The Scottish Premiership champions dominated proceedings but failed to turn possession into goals and had to wait until 84 minutes to break the deadlock.

Celtic struck the bar in each half through Kris Commons and Leigh Griffiths, before McGregor broke into the box and fired low past Reykjavik keeper Stefan Magnusson.

Murrayfield will play host to next week’s second leg, with Celtic Park unavailable due to the Glasgow Commonwealth games opening ceremony.

Deila fielded a strong starting 11 in his first competitive match as Celtic boss, handing a first team debut to McGregor, who spent last season on loan to Notts County.

He was the first to threaten the hosts and won the Hoops’s first free kick of the game.

The resulting ball in from captain Charlie Mulgrew found Virgil van Dijk at the back post, but the defender’s header was poor and went out for a goal kick.

The best chance of the match fell to last season’s player of the year Commons who struck a shot off KR’s crossbar.

Minutes later Commons forced Magnusson into a save at his left-hand post, although he failed to gather the ball as it went out for a corner.

KR threatened on the break through Gary Martin and Emil Atlason. Martin had the best chance for the Icelanders just before the half-hour mark, when he gathered the ball outside of the Celtic box before firing an effort that was comfortably held by Forster.

Deila’s side continued to press forward in numbers and once again it was Commons providing the spark in Celtic’s attack. The Scot played a one-two with Anthony Stokes, giving the Irishman time and space on the edge of the box, only to see his shot sail well over the KR bar.

A frustrated Celtic side went in at the break having failed to breach KR’s defences, in part through stubborn defending from the hosts but also thanks to poor judgement calls and a lack of match practice for the team as a whole.

Into the second half and Celtic came out of the traps the quickest, with Commons once again threatening the home side’s goal as a right-footed shot from the playmaker went just over the bar. 

Both Griffiths and Commons again had chances to break the deadlock only to see their efforts go over once again.

With full time fast approaching Deila brought on Teemu Pukki and Derk Boerrigter to give some fresh impetus up front, but it was 21-year-old McGregor who secured the win for the Scottish champions.

McGregor cut inside the KR defence on the right flank before firing a deflected effort past Magnusson, giving Celtic a deserved lead.

The Bhoys looked to extend their lead in the final minutes of the tie, but despite KR tiring, they could not find a second goal.

Deila’s side now take a valuable 1-0 away win in their home tie next Tuesday at Murrayfield.

But they will have to step up several gears to hit top form as Tuesday night’s performance was less than convincing.

Deila said he was “happy” to win the game “but most happy with the performance.

“Today was a step forward in the way we want to play and that is what I am most happy about. We deserved it, we deserved more. I am getting energy out of this, I like what I saw in the second half.

“I think (MCGregor) did well in his debut, in an important match like this. He has big talent but I want him to be more direct, go forward more and link up more with the full-back. But that will come and I am very happy for him that he scored a goal.”

Deila’s opposite number Runar Kristinsson was downheartened but felt the result was fair.

“It is still alive, 1-0 is nothing in football,” he said.

“It is going to be very difficult but, if we can defend well and go to Scotland with a good attitude, we believe we can do something there, at least give them another game, because I think we did that today.”