Ligue 1 leader PSG welcomes reigning champion Lille to the Parc des Princes on Saturday aiming to return to winning ways after last week's goalless draw with rival Marseille.
Mauricio Pochettino's side will do so without Mbappe, who played a full part in Le Classique but has since been struck down by an ear, nose and throat infection.
Mbappe was not the only superstar forward missing from training on Friday, with Messi also absent due to what Pochettino described as "muscle discomfort".
PSG will make a late decision on Messi's fitness and Pochettino has suggested he may field the Argentina captain through the middle, should he be fit.
"Messi missed training as a precaution," Pochettino said. "He did an individual session instead. We will see tomorrow if he can play.
"Kylian is of course important to us. As he is absent, there are several other possibilities over who plays through the middle.
"Messi can play there, but there are other alternatives. We'll have to see what the final decision is. As Pep Guardiola says, Messi can play anywhere."
Since arriving at PSG from Barcelona on a shock free transfer in August, Messi has played either on the right of a 4-3-3 or behind the striker in a 4-2-3-1.
Messi is still finding his feet in the French capital, the six-time Ballon d'Or winner having scored three goals in his first seven appearances in all competitions - each of those coming in the Champions League.
He is yet to score in Ligue 1, making this the first time he has failed to score in his first four league appearances of a league season since 2005-06 with Barcelona.
And with PSG failing to find the net in two of their last three league games, Pochettino was pressed on whether it is time to use Messi as the focal point of the attack.
"The tactical disposition of the team provides us with a base that can vary," he said. "We have a reference for offensive and defensive systems.
"Each player has, in principle, certain responsibilities depending on his position and that of others. Leo is a player who can play on the right, the centre or in the number 10.
"He is a player who can play anywhere. He is the best player in the world, who positions himself where the game demands it, according to the needs of the team."
PSG is also without the suspended Achraf Hakimi for the visit of Lille, while Marco Verratti will be absent for the next month and Sergio Ramos is still not ready for his debut.
However, Neymar is available after recovering from an abductor injury to play a part against Marseille.
Neymar has just one goal and two assists in eight games this season and Pochettino admits he is after more from the Brazil international.
"The circumstances are always different. The comparisons are not fair," he said when asked if Neymar is regressing from previous seasons.
"For me, Neymar is a player with enormous talent, one of the best players in the world.
"When we arrived at PSG, we tried to give him everything he needed. He needs to be at his best. I'm happy with him. For me, he's a player with enormous talent.
"We always hope that he will continue to improve. But this is not enough, because we know that we must continue to do better."
Asked if it was possible Neymar could be benched, Pochettino said: "All the players can be on the bench, or on the field. There are 33 players who think they are playing.
"If they are not playing, they are not happy. It is not only at PSG, but in the the whole football world. I couldn't give a clearer answer."
PSG has lost its last two games against 10th-place Lille in all competitions and could lose three in a row in this fixture for the first time since a run of four between March 1987 and September 1988.