Celtic midfielder Ryan Christie feared the referee was being swayed by the atmosphere during a controversial finale to their 1-1 Europa League draw in Rennes.
The Scottish champions had to hold on for a point with 10 men in stoppage-time after late substitute Vakoun Bayo received two yellow cards in quick succession.
After being booked for a dangerous aerial challenge, the striker's boot brushed against Edouard Mendy as the pair went for a loose ball, and the goalkeeper clutched his head and rolled about on the floor.
Spanish referee Jose Maria Sanchez indicated there was no foul before being persuaded to go over and see the goalkeeper, and he then blew for a foul and dished out a second yellow card, followed by a red.
Christie had been denied a clear penalty kick after being felled early in the second half, before levelling from the spot just before the hour mark after James Forrest was upended.
"I looked back and was waiting for the referee to give it and I was shocked when he didn't," he said.
"I looked at it in the changing room again and it was a definite penalty. It was a relief when we got James's one and evened it up.
"The red card was a bit strange because it happens and he blatantly waves it and says it was nothing. Then he goes over to the goalkeeper and changes his mind and sends him (Bayo) off.
"And as soon as Bayo is down the tunnel, the goalkeeper is up taking the free-kick straight away.
"I feel for referees because it must be hard to block out the atmosphere and keep in your own head, but we have got to do it as players. Going into the last 10 minutes of that game, it felt like if we put in any fouls, it could be a red card.
"It was difficult but you normally find that playing in these kinds of atmospheres."
Christie's goal was just reward for an ambitious display from the visitors.
"Overall we are very happy, we limited them to very few chances and created a few of our own," he said.
"We were desperate to get something. We knew how difficult it was going to be with how well they have started domestically.
"We were frustrated at half-time, after sussing them out and feeling we could definitely hurt them and not being able to capitalise on that."
Cluj shocked Lazio to win 2-1 in the other game and Christie believes the group is wide open.
"I said that before the game, with the standard of teams in this group, everybody can beat each other," the former Inverness player said. "It's going to be difficult to progress from this group.
"We have the experience of playing at Cluj and we know how hostile and how hard it is."