The Bianconeri won 3-0 in Glasgow, the first leg of the Champions League Round of 16.
"No, it's not done yet. It was a great game and a result that leaves us more relaxed for the next game, but Celtic are a strong side and we must approach it the same way," said midfielder Vidal.
"We saw they were a very physical side and I think we pressed them perfectly from the start.
"We expected it to be tough and it was. The result might not make it look that way, but we did not play the same way as we did against Fiorentina. In that game we played the ball more, whereas here we took a more tactical approach."