Brendan Rodgers said his players "gave everything" in Paisley
Celtic boss Brendan Rodgers said the officials did not have "one of their better games" as his side had a man sent off in a draw at St Mirren.
The champions lost Olivier Ntcham to a second booking in the first half.
It was a decision the Celtic manager described as "disappointing" in the wake of the 0-0 draw.
"Olivier had tracked back and conceded a free-kick just before, so I don't know if that was in the referee's mind," he told BBC Scotland.
"I think he is going across to slide in and block it, so when the guy goes down it looks like a tackle. But if you look at it again, there is barely any contact. So to get another card for that was disappointing.
"I don't like to go on too much [about officials]. It is a difficult game for them to manage. There were quite a few incidents tonight where their view of the game was quite different from most."
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'We had greater control with 10 men'
Resurgent under new manager Oran Kearney, St Mirren started brightly in Paisley as Celtic struggled to find their rhythm.
Rodgers acknowledged that slow start, but said the sending-off of Ntcham did not negatively impact the momentum of the match for his team.
The draw leaves Celtic two points behind Premiership leaders Hearts, who play on Saturday away to Motherwell.
"We didn't start the game well. We missed too many passes and didn't move it quickly enough," said the Celtic boss.
"I was disappointed with the sending-off, but the game didn't change much. If anything, we had greater control with 10 men.
"I thought we played well with 10. We tried to move them and tire them out, but just didn't have that final pass."
Rodgers refused to criticise his players despite the draw against St Mirren, adding: "The players gave everything on the back of an international break.
"St Mirren were always going to be spirited in Oran's first game. It's another clean sheet, it's a point.
"We wanted three but we just have to move on to the next game."