The result leaves Barca's chances of progress wide open.
Advertisement
Advertisement
De Jong said afterwards: "It was a game we had to win, but we have to do things much better. We have many things to adjust and we know it.
"We work on it, but we don't put it into practice on the field. We are weak against counterattacks because of issues with marking or defensive positioning."
De Jong says Barcelona's concern is "not all about" conceding fewer goals, "But if you concede three, it's difficult to win."
On Lamine Yamal, who struck on the night, De Jong added: "He's been doing well. He's a very good player. He's special. He always makes a difference. If he keeps working hard, we don't have to worry."