Brendan Rodgers’ side have been very competitive with a full quota of players in the Champions League but three red cards in four games have proved costly.

Daizen Maeda’s dismissal in Spain on Tuesday led to a 6-0 defeat by Atletico Madrid, which leaves Celtic bottom of Group E with one point and in need of wins over Lazio and Feyenoord and favours from Diego Simeons team.

Republic of Ireland centre-back Scales, who has not been booked in the Champions League, said of the red cards: “It’s probably that we are a young team and maybe a bit naive at times.

“You come and play in Europe and the referees, you get nothing out of them. They are a lot stricter and tackles that you might get away with domestically, they give.

“With VAR, you are going to pick up red cards in the way we’ve been doing.

“It’s frustrating, because I think with 11 players on the pitch we had started the game quite well.

“I know we had conceded earlier before the red card, but I thought we had quite a bit of the ball, and it definitely would have been a more even game with 11 men.

Scales also believes they need to learn from the animated reaction of the Atletico bench when Maeda made his tackle and was initially booked, before VAR intervened.

Scales said: “To be honest, you see the way they react and all of their staff are up off the bench. It definitely doesn’t help.

“The VAR screen is right beside their bench as well, and he [the referee] was probably feeling the pressure.

“They are definitely more street-smart than us, that’s for sure, the way they influence the referee.

“It’s not the nicest part of the game, but it helps them win games and we could definitely learn from it.”

The manner of defeat has led to some soul-searching among the Celtic support about their level in European football but Scales pointed out they had drawn with Atletico two weeks earlier.

“I think we’re at the level, it’s just naivety and poor decisions at times have let us down,” the former UCD and Shamrock Rovers man said.

“Some of the goals, we could have defended better, we need to look back on that and see what we could have done better defensively.

“But it’s still difficult with 10 men away from home to get results at any level, and especially there.”

Celtic now travel to Rome needing a win on 28 November.

“There’s a few games left in the group and now it’s just about bouncing back and doing as well as we can, because the Lazio game was so tight and it could have gone either way, and we feel that we can go there and get a result,” Scales said.

“It’s the same with Feyenoord at home. We were doing well in Feyenoord up until the couple of red cards, and the same happened here