Milan - Gianluigi Buffon believes Paris Saint-Germain (PSG) are not ready to win the Champions League as he prepares to make his European debut with the club against Napoli and play his first game in Italy since leaving Juventus.

The 40-year-old World Cup winner was suspended for PSG's opening three European games for his behaviour and comments towards the referee during Juventus' quarter-final loss to Real Madrid last April.

"To achieve certain successes we need a path, a project, a management and a team that have known each other for a long time," Buffon said in an interview with Sky Sport Italia.

"PSG have been renewed in recent years and need time."

Buffon said Lionel Messi's Barcelona and Juventus, who bought Portuguese star Cristiano Ronaldo last summer, were the favourites.

"In the Champions League there are two or three favourites - Barcelona, because they have the first or occasionally the second (best) player in the world.

"Then there is Juventus, who in recent years have consolidated at these levels and taken the other player who is considered the first and sometimes the second in the world.

"There are outsiders like the (Manchester) City... who have a coach and a team that make them one of the potential winners."

Qatar-owned PSG are third in Group C with four points, behind Liverpool (six) and Napoli (five), and will be battling for a win to salvage their flagging European campaign.

"It will be a delicate match against a very high level opponent," he said.

"The arrival of (Carlo) Ancelotti means this team now has a certain awareness that it's not certain they would have had before."

Buffon added it had been tough watching the first three games from the sidelines.

"I watched on TV in the dressing room, not being able to participate makes me suffer."

He said he still did not understand why he had been sent off by English referee Michael Oliver.

His suspension followed a post-match rant in which he said the referee had a "rubbish bin" where his heart should be.

"I really was in a foul temper and the Gigi from Carrara (his hometown in Tuscany) came out," said Buffon, who added he would laugh off the incident if he met Oliver again.

"I would joke, because irony is the best way to break down walls and immediately create empathy."