Luis Suarez praised Barcelona's response to falling behind after the Copa del Rey holders saw off Athletic Bilbao to reach the semi-finals on Wednesday.
Barca ran out 3-1 winners at Camp Nou - progressing 5-2 on aggregate - as second-half goals from Suarez, Gerard Pique and Neymar cancelled out Inaki Williams' early opener.
The hosts were on the back foot for long spells prior to half-time but eventually pulled clear after the break and Suarez paid tribute to a spirited Athletic display and his team-mates' response.
"You can never say anything until the end in these games," he told Movistar+.
"We left [the first leg] with a good lead but the opening goal made it complicated. The first half was bad but then we went on to win with a different attitude.
"Thanks to that we are still here. Athletic play the way they play and they press, it made our passing complicated."
Suarez was reunited with Lionel Messi and Neymar up front after his recent Copa del Rey suspension, but Luis Enrique was without Arda Turan due to illness, while Sergio Busquets and Andres Iniesta were named on the bench after suffering from fever this week.
Busquets was introduced for the final 20 minutes and Suarez refused to use injuries or illness as an excuse for Barca's slow start.
"[Busquets] is more than important in this team, as is Iniesta and Arda. But it's no excuse because we knew how we were going to play.
"We know that the supporters are the 12th man and their support was important to us. We were not playing well and wanted that extra support."