Arsenal manager Arsene Wenger admitted that his side are all but out of the Champions League after losing 2-0 to Barcelona at the Emirates Stadium on Tuesday.
The Gunners more than held their own against the Catalans, but a Barca counterattack in the 71st minute saw Neymar pick out Lionel to Messi to open the scoring, before the Argentine added his second from the penalty spot on 83 minutes.
"Of course I'm disappointed because we put a lot of energy into this game," Wenger said. "I felt that we lost at the moment that we looked more capable of winning the game, and we also lost it in a way which we could not afford to give them.
"It's a bit disappointing to give them the goals that we did, especially the first goal. I feel that we were extremely guilty and have no excuses for that goal. We were disciplined defensively but we knew that if we had to keep it at 0-0, we would keep it at 0-0.
"They are better than us, everybody knows that, but I think we could've won the game tonight if we kept the discipline until the end. Once again, like against Monaco, exactly the same thing happened. We were caught in exactly the same way.
"Barcelona master all aspects of the game. As soon as you're in a bad position, one or two players can punish you. We had two or three opportunities to stop the first goal which we didn't do because I don't think we had the right response to the situation that our players faced."
The defeat leaves Arsenal with a mountain to climb in the return leg at Camp Nou on 16 March, and Wenger conceded that his side's disadvantage means that the reigning European Champions have one foot in the quarter-finals.
"Barcelona are certainly through, 95 percent, but we want to go there and play," he added. "We are Arsenal Football Club and we will not go there to just have no chance. What we want is to focus on our next game. It's a shame that the players have not got any satisfaction tonight because energy-wise we put absolutely everything in."