Neil Lennon admitted it was a "sore one to take" after a cruel injury-time goal from Jordi Alba gave Barcelona a dramatic late victory over the Hoops in their pulsating Champions League Group G clash in the Nou Camp.
In the 18th minute Georgios Samaras' header from a Charlie Mulgrew free-kick went in off the back of Barca's Javier Mascherano to give the visitors a shock lead but a minute before the break Andres Iniesta levelled. With four minutes of added time almost played Jordi Alba broke Hoops hearts when he sneaked in at the back post to score from close-range.
The Celtic boss said: "I thought the team were magnificent. It is bittersweet really, it is hard to take losing the game in the manner in which we did but I am so proud of the players, I think they gave the club and country a huge shot in the arm."
He added: "There is a mixture of disappointment and anger that we didn't see it through to the end of the game.
"The players are hurting, they are angry, whatever you want to call it but it gave them a real a taste of playing in the Champions League at the highest level and they played fantastically well.
"No one gave us any hope but I think we have won a lot of admirers. They were brave, I couldn't ask any more from them, maybe just 30 seconds more to see it through.
"It would have been fantastic to pick up something from this game but we didn't budget for anything from it. I hope they take plenty from the game. It is tough to play at this level.
"But there are no recriminations and no criticism. I think we leave with our reputation intact."
Celtic remain second in the group with four points from three games ahead of the return game against Barcelona in a fortnight's time.