Barca took control of their quarterfinal with this first-leg win via goals from Lamine Yamal, Raphinha and a Robert Lewandowski brace.
Kovac conceded afterwards: "We expected more, but we have to be fair, and Barça took advantage of all the gifts we gave them. It was a deserved defeat, but it's also true that we could have scored a goal, especially in the first half, when we had a few chances.
“We have to look at what we can improve for the game in Dortmund, but we also have to prepare for the Bundesliga. I'm optimistic, but I have to be realistic... it was a very important result; our chances of qualifying are minimal.”
Asked if there is hope for Dortmund, he said: “We know it will be difficult, but yes, we must have a spark of hope, because without it it will be impossible.”
On if Barcelona are the best-performing team in Europe, Kovac added: “Yes, PSG too. I expect a good semifinal if they qualify, but we have to play them ourselves.”