Possibly the greatest front-three in football history - surely the French side would be impossible to stop.
However, that’s not quite been the case this season in Europe.
PSG have won just two of their five group matches this campaign and fell to a 2-1 defeat to Manchester City on Wednesday.
Okay, they have qualified for the last-16 but they will do so as runners-up.
And there was an almighty inquest following PSG’s loss to Manchester City - and it centred around the front three.
Jamie Carragher was strong in his analysis as he claimed PSG were ‘carrying’ Neymar, Mbappe and Messi due to their lack of defensive work
"I just don't believe teams can carry anybody now," Carragher began.
"Let's say the four teams who I think one of them will win the Champions League - Man City, Liverpool, Chelsea or Bayern Munich - they do not carry one passenger in the team.
"They [PSG] are carrying three, they've got absolutely no chance of winning the Champions League, Paris Saint-Germain, absolutely no chance."
Sitting alongside him, Thierry Henry was in agreement.
"If you want to win the Champions League, you cannot defend with seven players," Henry said. "It is impossible, I don't care who you are."
While Rio Ferdinand on BT Sport said: “I've never, ever played in a game where I've seen that"
So, what exactly were Neymar, Mbappe and Messi doing during the match?
Well, we’ve discovered one clip that sums it up in about 20 seconds.
Ander Herrera played a forward pass trying to release Mbappe but it was too heavy and Ederson came out of his goal to clear. But instead of Mbappe and Neymar closing down the City goalkeeper as he attempted to play it out from the back, he couldn’t have looked more uninterested.
The ball is then played out to the left and Raheem Sterling picks it up ready to attack PSG’s defence. Messi could pressurise the winger but decides not to and continues to walk.
VIDEO: Messi, Neymar and Mbappe's lack of defensive work
City are suddenly on the attack.
It was just one example during the 90 minutes but there were numerous occasions the three superstars failed to work hard enough for the team.
Of course, they are fantastic players and they combined beautifully for PSG’s goal on the night.
But as Carragher, Henry and Ferdinand said, they simply can’t afford not to defend in the Champions League.News Now - Sport News