Thiago Silva feared Paris Saint-Germain had blown their Champions League chance before rallying to qualify as Group C winners.
One victory from their opening four round-robin matches left the Ligue 1 champions staring at elimination but a hard-fought 2-1 win over Liverpool in Paris preceded Tuesday's 4-1 triumph at Red Star Belgrade.
Kylian Mbappe, who scored PSG's fourth in the Serbian capital, told reporters Thomas Tuchel's squad had unleashed a few home truths upon one another following back-to-back draws against Napoli.
But Brazil centre-back Thiago Silva conceded he felt the damage had already been done.
"The goal is achieved. I was a little scared this year that we would not go to the round of 16 because it was difficult," he said, as quoted by L'Equipe.
"But in the difficulty, there are positive things. I'm happy with the last matches we did. I think mentally, since Naples, we have changed a lot.
"The draw in Naples was my fault. For the Liverpool game, I pushed the players a lot because I felt they needed it.
"If we had conceded a draw against Liverpool, we were almost eliminated. But we managed to win against a team that can still be a finalist this season. We beat them."
The 34-year-old added: "Today was a little easier. When Belgrade scored, we stayed calm, patient.
"I feel we play more like a team. I hope we will continue like this until the end of the season."