Ross County midfielder Jackson Irvine believes referee Willie Collum may have cost the Staggies a dream start to the season at Parkhead.
Irvine appeared to have been denied a goalscoring opportunity when he was brought down by Celtic goalkeeper Craig Gordon on the edge of the area 23 minutes into the first half.
But the Scotland international escaped with a yellow card when a red seemed a more likely option – much to the chagrin of the Ross County players.
The Hoops were 1-0 ahead at the time thanks to an early Leigh Griffiths penalty and went on to put the result beyond doubt with a Stefan Johansen goal 10 minutes before the break.
But former Celtic player Irvine said a red card for Gordon would have had a major impact on the eventual outcome of the match.
The Australian midfielder said: “It was a game-changing incident. I spoke to Craig after the game and he seemed relieved at the time. It was so early in the game and would have changed things had they lost a man at that point.
“I saw him coming and he was always going to bring me down when I knocked the ball past him.
“You can look at it in different ways but, for me, if he hadn’t come off his line I would have one on one with the goalkeeper.
“The fact he came out and halted me was a denial of a goalscoring opportunity and a red card. That’s my view but not everyone agrees.
“For the referee, it was flag day at Parkhead and it’s a big decision to make in front of the home crowd. But I still think Craig should have had the red card.”
Irvine, who joined County on a permanent basis last week from Celtic having spent last season on loan at Victoria Park, claimed his team could be proud of the way they matched the Hoops in a much-improved second-half display.
He added: “It’s an interesting feeling. Some teams would be pleased to come away with a 2-0 defeat at Parkhead but we are a bit disappointed.
“I don’t think we showed enough belief in the first half, although losing a goal so early killed the game plan.
“Defensively we were quite sound and in the second half we started to believe we could score a goal. I don’t think that was the case in the first half, which was a disappointment.
“This game was a good opportunity to test ourselves against the champions.
“It set a marker for our level on the first day and we created some good opportunities and played some nice, flowing football.
“I’m disappointed with the result but pleased with the second half and it was a good building block for the rest of the season.”