Marchisio, who notched the second goal of the evening, told reporters after the match how his side had all but secured their spot for the quarter-finals.
“It is a very important victory, especially as we can be a little more concentrated on Serie A. We haven’t passed through yet, but it is a great win in a difficult arena and we put in a fine performance.
“It’s true it is tough to overturn a 3-0 away win, but we must never be certain and always go out there with the same determination."
The 27-year-old is delighted with his side's unbeaten Champions League campaign and believes that Antonio Conte's tactics worked to full-effect against Neil Lennon's side.
“This team is having a great Champions League. This was an important signal to ourselves and nobody else. It was crucial to come here and score a goal, but we ended up getting three.
“We saw they scored many goals from corners and with crosses into the box, so tried our best to make it difficult for them.
“It is their nature to be gritty and physical, but we gave as good as we got.”
Conte admitted that he made various tactical decisions for the match and was delighted that they paid off.
“In the first half I told the lads it was dangerous for us to sit too deep, so Arturo Vidal and Marchisio were crucial to push it up and take the defenders with them. I worked a lot on that aspect," he revealed.
“We changed something compared to our usual defending, as they had scored 40 per cent of their Champions League goals from corners and set-pieces. We were only surprised once with a header over.
“We did pretty well defensively apart from at times in the first half when we went too deep. It was a good performance, we knew Celtic were a good side and they might not be mentioned among the top teams in Europe for many years, but they beat Barcelona and eliminated Benfica and Spartak Moscow."
Conte went on to praise the deafening atmosphere at Celtic Park and the 43-year-old was delighted with the way in which his players coped with the Bhoys' 12th man.
“It was certainly a very important victory. I personally as a player have been in this competition for many years, but had rarely seen a passionate atmosphere like this," he added.
Chile international Vidal was equally thrilled with the scoreline but admits that it does flatter the Italian champions.
He said: “I think we played exactly as we had to play tonight because Celtic are tough opponents, especially when they play at home.
"If you look at the result you think it was an easy game for us, but I can say it was not like that at all. They were very dangerous especially from corners and set-pieces. We did well to control their attacks and then hit when the chances came in the late stages.”