Brendan Rodgers felt his Celtic team showed they can compete at Champions League level before inexperience played its part in their Group E opener against Feyenoord running away from them following two red cards inside five minutes.
Both Gustaf Lagerbielke and substitute Odin Thiago Holm were sent off on their Champions League debuts with Celtic trailing to Calvin Stengs’ 30-yard free-kick in first-half stoppage-time.
Joe Hart saved a penalty in between the red cards before Feyenoord went on to win 2-0 in Rotterdam.
Rodgers said: “We showed in the game that for this tournament we are going to be competitive.
“We started really, really well, for the first 60 minutes the game was very close. I thought we looked a threat and progressed the ball well into the final third. Maybe with better decision-making and releasing the pass we would have given ourselves the opportunity to get in front.
“I’m disappointed with the first goal, we should never be conceding that, especially at that moment.
“But it was even for 60 minutes and unfortunately we got two players sent off. It’s really difficult at this level with 11 against 11, but with 11 v nine, it’s difficult.
“But I have to applaud the players for their spirit and mentality, they kept going. It was harsh on them.”
Hart was left exposed by his wall for the opener, with Kyogo Furuhashi inadvertently jumping out of the way of the ball, and the curl on the shot took the ball away from the goalkeeper after it bounced on the wet turf, although he got a hand to it.
Rodgers said: “We talked about it inside. I like the players to make decisions and there was a decision within the game to change the wall. But you have to make sure the wall is correct or else you get done.
“It’s a very, very small detail but if you don’t look after it, you end up beaten. It was bitterly disappointing because we played well up to then.”
Rodgers felt both red cards should have been avoided. Lagerbielke received a second yellow after catching Igor Paixao in the throat with his arm as he tried to jockey the forward. Holm was shown a straight red card for lunging in to a high tackle.
Rodgers said: “With Gustaf, there was no drama. The ball was running through to the goalkeeper. I think it’s inexperience, just let the ball run through. I still thought it was a bit harsh but I can maybe see why the referee gave it. But we can avoid that situation for sure.
“The second one, he is young and committed but at this level you can’t go to ground. When I saw it back, his foot is up. At this level you get punished for that.
“Obviously they are bitterly disappointed afterwards, their first experiences of games at this level. They will learn from it.
“Gustaf had done well up to that point, two inexperienced centre-backs – I thought Liam Scales was outstanding and Gustaf had been coping well.”