Barca's ambitions of pulling off the unprecedented feat of overturning their 4-0 first-leg deficit were on track when they led by three goals at the Camp Nou, but Cavani's 62nd-minute goal left them needing three more.

Luis Enrique's men did just that, though, in the final seven minutes of the game to snatch a quarterfinal berth from under PSG's noses, though Verratti told media even Barca had not believed they could do it.

"Barca deserve to qualify," the Italy international said. "It was difficult to play, to make passes. They pressed too much in the first half. In the second half, we managed to play better. But we conceded the third goal and we understood that we had to play. We couldn't wait for it to finish like that.

"After Edi's goal, we were calmer. I spoke to the Barca players -- they told me it was over. I don't find any explanation for conceding three goals in five minutes. That's football. It's a match I'll never forget. I hope it'll serve as a lesson for everyone."

He added: "We're going to have difficult moments. There will be others. We have to find the strength to pick ourselves up. We have to be men. We're all sad. We lost 6-1 -- it wasn't the referee's fault. We're the first ones responsible for this."

Marco Verratti shows his disappointment after PSG's 6-1 second-leg defeat.

The French champions were a pale shadow of the side that had dominated the first leg in Paris, completing just 183 passes and having only 35 percent possession as Barcelona swept over them, setting the platform for their incredible win with Luis Suarez's third-minute goal.

Layvin Kurzawa's own goal before the break and Lionel Messi's penalty after it made it 3-0, and after Cavani had seemingly revived PSG, Neymar found the net twice before Sergi Roberto scored five minutes into added time to take Barca through.

"It's not a problem of confidence," PSG captain Thiago Silva, who missed the first leg through injury, said. "In the first leg, we played with control, we played a great game, with personality. We played with almost the same players today, in a white-hot atmosphere, but we lacked personality."

The Brazil international added: "When you try to play the ball out from the back and you can't, after that it's more difficult. So we started to clear the ball, giving it back to Barca and trying to play on the counter-attack, but we didn't manage to do that. It's tough, it hurts everyone, but we have to lift our heads."