It was almost half time at 0-0, but then something bad happened. Pique gave the ball away, Yannick Carrasco darted in and Marc-Andre ter Stegen rushed out, and was nutmegged, a long way from his goal. The Belgian ran onto the ball and scored into an empty net.
It was a mistake to rush out because Lenglet was covering, although the blame for the goal lies on other players, including Pique too. Carrasco's magic touch left Ter Stegen done for.
However he had also made a brilliant early save from Saul Niguez, as we are used to seeing the German stopper do. It helped Barca stay afloat under Atletico pressure. Ups and downs.