"It's always a pleasure to meet again, to see him as anxious, despite his age, with great respect for friendship and affection for my friend," Ancelotti said.
Buffon, 40, will make his debut for France against 55,000 fans at San Paolo Stadium in his first Italian game since leaving Juventus in the summer.
"Even if the first legs would be 2-2, we would have to play well at the end and we would need to do something extraordinary to beat Paris," said Ancelotti, who coached PSG between 2011 and 2013.
Napoli are second in Group C with five points after three games, one of Liverpool's leaders.
PSG is facing the prospect of recovering from a threefold fourth round.
"The club is very balanced and uncertain, which is very good," Ancelotti said.
Napoli announced that Ancelotti won the Champions League, won twice in the 2003 and 2007 campaign, with Real Madrid in 2014 – to counter PSG, with the two most expensive players in the history of Neymar and Kylian Mbappe.
"We know the problems, the importance and the things we need to do tonight," Ancelotti said.
"They are still a strong team, they are very difficult to deal with, and they are completely unpredictable.
"Working very well in the first leg gives us a lot of respect, but still a difficult game.
Meanwhile, Ancelotti said PSG had no plans for the Ligue 1 side in 2013.
"There are many variations, the team is under construction, but now the project has reached the last level."