Barcelona coach Xavi admits they "lacked calm" in the second-half of defeat at Manchester United.
Barca are out of the Europa League 4-3 on aggregate after losing 2-1 at Old Trafford on Thursday night.
Xavi lamented, "We lacked calmness in the second half. We needed to show more patience. We lost the game due to details.
"Their two goals came from balls we gave away.
"In general we played well, we competed and gave a good go of it against a top team but it's a shame we lost.
"United's first goal did us damage. We won fewer of the duels in the second half. They went up in intensity."