Brendan Rodgers says his Celtic players have earned the right to their Europa League place but can learn a lot from their Champions League group games.
A 1-0 defeat to Anderlecht at Celtic Park in the final group match brought mixed emotions, with disappointment about the performance and score on the night weighed against qualifying for the knockout stages of the Europa League.
Rodgers saw progress to European football after Christmas as the main result of the night but said his team have "a hell of a lot of work to do" if they are reach a higher level.
He said that Anderlecht deserved their victory and that the mental context of the match may have been to their benefit but his players hadn't stepped up on the night.
"We've achieved our overall objective, which was to qualify, which is absolutely brilliant for us but there's lots of lessons to take from the whole group stage and look to put that into the Europa League after," he told STV.
"There's technical lessons [to take]. We've a lot of the players playing domestically and doing great but maybe have more time on the ball and when they get to this level they have to have the ability to play quicker.
Also, there's continuing to show that belief in how you play.
"So lots of lessons but the players have achieved the overall objective which at the start was to get to the Europa League. We've done that having been the fourth seed in the group so it's a great testament to the players in getting through and there's still a hell of a lot of work to do."
Assessing the group stage overall, where Celtic suffered heavy defeats to PSG but also recorded an impressive 3-0 away win over Anderlecht, he said there was progress from last year's involvement in the elite competition.
"We're making improvements," he said. "There's harsh lessons for us because of the level of the opponent and the quality.
"It's always going to be a real tough ask for us but to get through to this stage is a huge achievement for the players . They deserve a great amount of credit.
"They won't feel good tonight because we've lost a game but if you look over the course of the six games we had a great result out there, we've put in some decent performances and not got results. Tonight, the best team won but we'd done enough out there which away in Europe is a tough thing to do.
"So we've earned the right to be there and we won't get carried away because there's still a hell of a lot of work to do at this level."
Celtic go into Monday's draw for the Europa League last 32 but Rodgers was cautious about raising expectations that they could go deep into the competition.
"I'm not sure," he said. "There's still too many teams that are much better than us in there so we have to be realistic but we'll improve over the next couple of months and let's see what the draw brings."