Paris Saint-Germain were grateful to a last-minute howler from goalkeeper Paulo Gazzaniga as they snatched a 1-0 win over European debutants Girona in their opening game of the new-look Uefa Champions League on Wednesday.

PSG had over 60 percent possession and 24 attempts on goal but looked set to be left frustrated by their opponents at the Parc des Princes until a low Nuno Mendes cross squirmed under Gazzaniga and into the net in the 90th minute.

It was a harsh ending to their Champions League bow for Girona, who qualified for Europe for the first time in their history after a historic third-place finish in La Liga last season.

PSG missed chance after chance in the second half and looked set to draw another continental blank, just like in their semi-final defeat by Borussia Dortmund last season when they somehow failed to score in either leg.

However, the late goal allowed PSG manager Luis Enrique's team to continue their perfect start to the campaign as they aim to go further than last season's run to the semis and win European football's biggest prize for the first time.

"Girona defended very well and showed why last season they led La Liga for so long. They are a better team than many in the second or third pot of seeds, even in the first pot," said Enrique.

"We were much better in the second half," he added. "We got a bit of luck with the goal but I think we deserved the victory."

The Champions League has been radically changed by Uefa, with all clubs in the new league phase now playing eight matches against eight different opponents.

The top eight will advance to the last 16, with clubs finishing from ninth to 24th in the standings going into a play-off round to decide the remaining last-16 spots.

PSG's next game will be away to Arsenal on October 2. (AFP)