Andres Iniesta rued Barcelona's capitulation as they were held to a second successive La Liga draw with Deportivo La Coruna on Saturday.
The Liga leaders were 2-0 up against Victor Sanchez's side thanks to impressive strikes from Lionel Messi and Ivan Rakitic, but shipped two late goals at Camp Nou.
After Santi Mina's 86th-minute strike for Valencia cost Barca a win last weekend too, Iniesta believes they must work to cut out such errors.
"The end is unexplainable, we lost control when we needed it and facilitated the opposition," he told Canal Plus.
"These things happen, we analyse it so that it doesn't happen again. The last two weeks we've lost four points, which makes things tighter.
"Now we change mindset because we are playing for a title and have to think of what's next.
"We had a 2-0 lead, the match was good. We lost the control we had throughout the match and two points escaped us."
Atletico Madrid could move level with Barca at the Liga summit if they overcome Atheltic Bilbao on Sunday.
