At various points during his post-match press conference in the wake of Tuesday's 7-1 defeat to Borussia Dortmund, Brendan Rodgers mentioned learning from the defeat.
It's not the first time Celtic have been on the end of a devastating result at the highest level of European football, nor is it the first time Rodgers himself has carried the can as manager.
Tuesday night's result marked the third time the Irishman has seen his side concede seven goals in the Champions League – having first lost 7-0 to Barcelona during the 2016/17 campaign, and then losing 7-1 to Paris Saint-Germain the following year.
After Dortmund, Rodgers underlined the fact he will not change his style of play in Europe, even against the best opposition on the continent.
Are Celtic learning? That's not an easy question to answer, however here's what the Celtic manager said following his side's previous two biggest UCL defeats during his first spell in charge at Parkhead.
Post-match after Barcelona 7-0 Celtic, during which Lionel Messi scored a hat-trick, Neymar assisted four times, and Celtic missed a penalty. Celtic entered this match off the back of a 5-1 Glasgow derby win three days earlier.
"We put a huge effort into the weekend and got a fantastic victory," said Rodgers. "It was always going to be really tough in this game to play probably the best possession team in the world.
“In the first half we had a critical moment in the game when we won a penalty [missed by Moussa Dembele]. We went 1-0 behind very early, but we then had a great chance when we got the penalty and I think if you get it to 1-1 then it makes it a little bit nervy, especially after them losing here weekend.
“But of course not long after that they got the second goal and then in the second half we just ran out of legs.
"The game at the weekend – added to their immense quality – makes it very difficult and the score-line by the end was bitterly disappointing. But there was a lot to take from the game for the players in terms of technique, in terms of simplicity and quality and lots of things to learn for them.
"It is always going to be a long night when you are up against that kind of quality but what you have got to do is to try and give them something to think about for a little period.
There were one or two periods in that first half when we broke through and we looked a threat,” said the Celtic manager. “I thought Scott Sinclair was outstanding with his quality and his work-rate and then we got a penalty.
“If you put that away. . . you don’t get many opportunities at places like this here so you have to be able to take that opportunity. Unfortunately for young Moussa the goalkeeper has read the penalty and then they scored to make it 2-0 and it is very difficult then."
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Post-match after PSG 7-1 Celtic, during which Celtic scored in the first minute. Celtic lost 5-0 to the French side at home earlier in the campaign, and were still in the midst of their 69-game unbeaten domestic run. Four days after this loss, Celtic won the League Cup final 2-0 against Motherwell.
"I am certainly nowhere near as disappointed as I was funnily enough against Barcelona last season.
"We conceded seven goals over there when I first came in and I was very, very disappointed after that, but in a strange way I thought there were a lot of good moments in this game.
"We scored, started with good intent, got the goal, and you could see the belief in how we were playing and defending. But we gave the ball away in midfield and that gives them the opportunity to get the goal. The spell after the first goal is probably the bit we are most disappointed with.
"Sometimes with the ball we gave it away too cheaply, but there were lots of other spells where we showed our confidence," Rodgers added. "And you also have to admire the sheer quality of PSG, you can’t not admire that. I think they only had 11 shots, but seven of them went in, with big quality. I would be very surprised if they don’t at least reach the Champions League final.
"If you think of the first goal, you lose possession of the ball. In lots of the games you will get away with it, give it away against this team and they will punish you. Celtic players have a good technical level but against a superior team like PSG their technique is at a slightly higher level and when you’re chasing the ball you tire a bit in the game. What you are watching here in Paris is the world’s best.
“Of course with professional pride, losing seven goals, you are not so happy. People who didn’t watch the game and score, they think 7-1. But there were enough positive moments in it.
"Sunday, like it always was, is going to be a very important game. But I told the players afterwards that they gave absolutely everything. And we will be absolutely fine for Sunday [the League Cup Final, which Celtic won 2-0], we are disappointed of course, but even more determined now to win on Sunday."
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