Luis Enrique felt Barcelona were spectacular in the first half against Manchester City despite eventually losing 3-1.
Lionel Messi gave the Catalan side the lead in England and they had chances to add to their tally.
However, they were punished for missed chances when a Sergi Roberto area set up a City move which ended with Ilkay Gundogan slotting him Raheem Sterling’s pass.
Barça boss Luis Enrique was happy with what he’d seen until then, but felt too many mistake crept in from that moment on.
“We played 40 spectacular minutes, especially on this stage against a top rival,” he told a news conference.
“But we committed a key mistake and that hurt us because we are not machines.
“It’s a shame that we have made that error for the first goal and from there on we had a tough time.
“When you concede like that, it’s normal that you have a bad spell.
“During that moment we wanted to continue to dominate the game, but it wasn’t possible because of errors we made and pressure from City, too.
“We didn’t have much of the ball and City took advantage of our errors.”
Despite the defeat, Barça still lead Group C with nine points, two ahead of Manchester City.
They play in Glasgow against Celtic later this month and a win will seal their place in the last 16.