A clearly frustrated Arsene Wenger accused his Arsenal side of naivety in their 2-0 Champions League loss at home to Barcelona.
The Premier League team face an uphill task in the second leg of the last-16 tie at the Camp Nou next month after a second-half brace from Lionel Messi kept Barca on course to retain their European crown.
But Wenger was frustrated to see Arsenal pass up chances to open the scoring, with Alex Oxlade-Chamberlain scuffing their best first-half opening.
An Olivier Giroud header almost broke the deadlock for the home side after 60 minutes but Wenger lamented his team's willingness to pour forwards on the back of that opportunity, with Messi's first goal arriving 11 minutes later.
Mathieu Flamini fouled the Argentina superstar seven minutes from time and he duly doubled his tally from the penalty spot, leaving Wenger to compare elements of a largely creditable display to last season's humiliating home defeat against Monaco at the same stage.
"Well, Barcelona is a great team but we knew that before that game," Wenger told BT Sport. "We put a lot of energy into the game; I believe technically we were very average overall.
"The regret I have is that once we looked like dominating the game we gave the goal away.
"Similar to Monaco, we were naive. It is frustrating because we looked like winning this game and threw it away.
"That makes it realistically very, very difficult - if not impossible [to go through]. But we have to go there and fight.
"In the final 20 minutes we had the chances but we didn't score; in the first half we had chances."
Seeing Barcelona's lethal forward trio of Luis Suarez, Neymar and Messi combine on the counter-attack to open the scoring was an aspect Wenger found particularly galling.
"They are lethal. One thing we couldn't afford to give them was counter-attacks because they are very dangerous. That's exactly what we did," he added.
"We pushed too far in their half and got caught. That's the quality [of Barcelona] as well.
"It's too easy to [assign] blame, I think you have to respect the effort the players put in. What is frustrating is that it looked like they might tire.
"I knew in the last 20 minutes we would have a chance to win the game if we didn't make any mistakes and that's the frustration of the night."