Celtic striker Leigh Griffiths will shrug off the frustration of Friday night's Ladbrokes Premiership stalemate at St Mirren to refocus on Europe.

The Hoops dominated after being reduced to 10 men in the 37th minute – when midfielder Olivier Ntcham was sent off following a second yellow card – but were held by the battling Buddies in what was Oran Kearney's first game as Saints boss.

Griffiths, who signed a new deal until 2022 on the day of the game and who came on as a second-half substitute, admitted his disappointment but is now looking to the opening Europa League Group B game against Norwegian side Rosenborg at Parkhead on Thursday night.

He said: "Yes we were frustrated. Playing a large part of the game with 10 men, we dominated the game.

"At times you are not going to get clear-cut chances but sometimes you need to take those half chances you get.

"You have to give credit to St Mirren, they were resolute and were difficult to break down.

"We have a good week's training and we look forward to a big game against Rosenborg."

The Scotland striker, who was denied a last-gasp winner by the offside flag, was more than happy to sign a new deal with the Hoops, whom he joined from Wolves in 2014.

The 28-year-old said: "I am delighted to get it over and done with.

"It has been a long time coming and I was unfortunate not to cap it off with a goal.

"But it is done now and I can focus purely on my football.

"I thought it was really tight. I was looking back and it I was probably half a yard offside.

"I had a chance earlier in the game that I should have buried with my right foot but it wasn't to be and you have to give credit to St Mirren for the way they defended."

Griffiths knows he will be battling with Odsonne Edouard for the main striker's place but welcomes the challenge.

He said: "The big man is playing well. I can't fault him for what he is doing.

"He has got the shirt just now and I need to try to take it off him. He played well last night and was unlucky with a couple of chances."