An 18th-minute Georgios Samaras' header from a Charlie Mulgrew free-kick went in off the back of Barca's Javier Mascherano to give Celtic the lead but a minute before the break Andres Iniesta equalised. With four minutes of added time almost played at the end of an exhausting evening in which goalkeeper Fraser Forster had been outstanding, defender Alba sneaked in at the back post to knock an Adriano cross past Forster from close range.
"I thought the team were magnificent," said a proud Lennon. "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. 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 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.
Lennon believes his side still have a chance of going through to the knockout stages of the competition.
"You have to look at the three performances so far; we have done very well. There are three games to go so anything can happen. I don't think they will take a lot of picking up, they can take a lot of satisfaction from this performance.
"The next game is Barca at home and we have to be mindful of that. We don't want to go gung-ho but we will have a big crowd and that will spur us on."
Tito Vilanova, the Barcelona coach, was not surprised by the tenacity of the Scottish champions but insists his side were not lucky to win the match.
"Like I said yesterday, we knew Celtic were dangerous, they were fast and powerful in the air. But I don't think it was luck. Normally, when you score at the end it is but I think we had bad luck before that.
"I think we deserved to win the game; their goalkeeper played well and credit to them but I think we controlled them pretty well. It says a lot about Barca, we keep going and if you don't have any attempts on goal you won't win.
"But I believe that Celtic have a chance to qualify; they have two more matches at home so it is possible that they can go through."
Kelvin Wilson reflected the mood of the Celtic players in a single word. "Gutted. We defended with our lives all game and it looked like we'd done it. But it's never over until the final whistle with Barca and they proved it."
"I tried [to stop Messi]," he said. "I feel I did okay but the whole team defensively did brilliantly. It's a team game, not an individual game.
"We're gutted more than anything. It's the last minute of the game and you try to see it out. We'll learn from the mistakes and hope next time we can complete it."
Forster, gleaned litle consolation from being named man-of-the-match.
"In the end, everyone is devastated," he said. "We just had to defend one more cross and we weren't able to do that. But we've shown what we can do on a European level. We deserved a point, but when you're playing Barcelona there's a lot of defending to do. They never stopped for 94 minutes.
"Everyone has given 100%. It's nice to make saves but we didn't hold on for the point, so they're meaningless at the end of the day. I would have swopped it all for a point."