The Catalan giants had been looking to make it three straight league victories under Xavi's management, but a 79th-minute effort from Juanmi handed Betis a 1-0 victory at Camp Nou.
Xavi has conceded that Barcelona "have to improve", but the Spaniard has claimed that the defeat was "too harsh a punishment" considering how the match unfolded.
"When we were at our best, the goal came on the counter," Xavi told reporters. "You have to be more tactical. They shouldn't catch you [off guard] on the counter.
"We knew about their transitions. We had a few good minutes. It is too harsh a punishment for the game we have played. It is a defeat that hurts. At home. We were in good form, but that's how football is.
"We have to dominate the games more. We have to stop counters. These are situations that we have to control. It has been unfair. This is the Barcelona we want, but we have to improve. We have to be tactically smarter."
Barcelona will now head to Germany to face Bayern Munich in the Champions League needing to win to guarantee their spot in the knockout round of the competition. body check tags ::