Celtic manager Brendan Rodgers said the experience of competing against some of the best players in Europe would prove invaluable for his young side after their Champions League exit.
Rodgers looked on from the touchline as Lionel Messi inspired Barcelona to a 2-0 win over the Scottish champions at Celtic Park on Wednesday to book their place in the last 16.
Celtic can no longer secure even the consolation of a Europa League berth, but Rodgers said his side would learn a lot of lessons from their foray into Europe's elite competition following a two-year absence.
"First and foremost, the challenge was getting into the Champions League," said Rodgers, whose side visit Manchester City in their final group game next month.
"Celtic had gone a period of time without qualifying, so we made a huge effort in the summer to qualify.
"There is still one game to go in the competition, but this experience was always going to be invaluable to us. We've got some young players in the team who are going to improve thanks to this.
"I think if you look at the first game (Celtic's 7-0 loss at Barcelona) compared to tonight (Wednesday), we weren't fearful tonight. They pressed well and tactically the players improved.
"It's just about maintaining that standard. They've played three of the best teams in Europe during the course of this competition and we've gradually got better with each game."
Messi, who missed Saturday's goalless draw with Malaga due to illness, provided a fine finish to Neymar's lofted pass to hand Barcelona a 24th-minute lead.
The Barca captain, who grabbed a hat-trick in the 7-0 mauling in the reverse fixture, then converted a 56th-minute penalty won by Luis Suarez, leaving his side top of Group C with 12 points from five games.
However, Rodgers, who managed Suarez at Liverpool, felt his former player had conned referee Daniele Orsato.
"I didn't think it was a penalty. What Luis is brilliant at is around the box he provokes the defenders," Rodgers said.
"I think that he's leaning into Emilio Izaguirre, who is trying to fight for his space. And what Luis is clever at is he grabs hold of the defender and spins round and it looks like he's been pulled to the ground.
"It was a key moment in the game as at the start of the second half we were pressing and we were winning the ball and the momentum was clearly with us."
Barcelona manager Luis Enrique, whose side have made their worst start to a La Liga season since 2004, was pleased to top a tough group above Manchester City and Borussia Moenchengladbach.
"It was quite a hard game and we expected Celtic to come out and make it difficult," he said.
"We were good at the back and we got better as the game went on. Messi, as usual, was at a very high level.
"It was a very difficult group and it's great to finish first with a game to spare."
Neymar appeared to be fortunate to escape with just a booking in the match, which will see him miss Barca's final group game, as he pushed Mikel Lustig to the turf after the players had clashed.
The Brazil star had earlier learnt that Spanish prosecutors are seeking a two-year jail sentence and a 10 million euros ($10.6 million) fine against him for his part in his allegedly fraudulent transfer to the club.
He was subbed moments after clashing with Lustig, but his manager played down the incident.
"It was just in the last five or 10 minutes that there was maybe a bit of an issue with Neymar with regards to the crowd shouting," Luis Enrique said.
"It was maybe just handbags with the Celtic player and nothing too special."