The French champions start the defence of their Ligue 1 title against Caen at the Parc des Princes on Sunday, and all eyes will be on Neymar after he missed the final three months of last term with a foot injury.
The world's most expensive player has been the subject of consistent speculation linking him with a move away from France, with reports usually suggesting he will sign for Real Madrid, but he insists that he's not done with PSG yet.
"Yes, I will stay in Paris. I have a contract with PSG. The speculation? The majority of it is invented by the press," Neymar told ESPN Brasil last month.
"I have a contract and people know the objective, the reason why I went to PSG. I want to win with this club and I hope this season will be wonderful."
Neymar returned in time for the World Cup, but failed to inspire Brazil to a record-extending sixth title as they suffered a 2-1 quarter-final loss to Belgium.
Mbappe, on the other hand, was named as the tournament's best young player after scoring four goals -- including two in a scintillating individual performance against Argentina -- to help France lift the trophy.
The 19-year-old capped it off by becoming only the second teenager in history after Pele to score in a World Cup final, netting in the 4-2 victory over Croatia in Moscow.
The transfer fee of 180 million euros which PSG paid Monaco for Mbappe is not far behind the world-record 222 million euros they parted with for Neymar.
Mbappe can 'mark history of football'
New arrival Gianluigi Buffon believes that Mbappe can follow in Pele's footsteps by becoming an all-time great, having played against his then-Monaco team in the 2017 Champions League semi-finals for Juventus.
"When I spoke (after the match) with (Juve centre-back) Andrea Barzagli, who is one of my great friends, he told me 'Gigi, in 20 years of my career I have rarely seen a player run so fast with the ball, I had a hard time stopping him'," the 40-year-old Buffon told PSG's club magazine.
"These words are not insignificant because Barzagli, when he is focused and fit, is really a top defender.
"It's obvious (Mbappe) has something more than others. I hope he will remain humble and keep this desire to progress and make sacrifices.
"If so, he will make a mark in the history of football and write incredible pages of the sport."
Further accolades seem sure to follow in the coming years for Mbappe, who was named on the 10-man shortlist for FIFA's 'Best Player' award for 2018, with Neymar conspicuous in his absence.
But the 25-year-old Neymar, despite criticisms over his playacting at the World Cup, did perform on the pitch last season, scoring 28 goals in 31 appearances for PSG before breaking a bone in his foot against Marseille in February.
Neymar will likely want the spotlight, but his best chance of leading PSG to their stated goal of a first Champions League title will be to replicate his famous combination with Messi and Luis Suarez at Barcelona with Mbappe and Edinson Cavani.
Despite a domestic treble last season, that never really came to fruition, as Mbappe took time to settle in and Cavani and Neymar rowed over penalties.
But new coach Thomas Tuchel said when he took over from Unai Emery in May that he was "not afraid at all of stars", adding that "in his experience they are the hardest workers".
A second straight league title should be little more than a formality, but PSG will need their big guns on the same page and firing if they're to finally lift the European crown.