Forwards: Lionel Messi, Carlos Soler, Kylian Mbappe
With four defenders and three midfielders, there are three open outfield holes to fill in the lineup. Mbappe isn't resting any game as the leader of PSG, and basically because he knows he's the face of the club, and the man tasked with leading the entire squad forward no matter what, let alone after another Champions League failure.
Lionel Messi might demand a rest, more on fame and stature than actual fatigue, so we'll see how Galtier deals with his egocentric superstar. With just a bunch of Ligue 1 games remaining on PSG's schedule from now on, though, Messi should just keep his head low, play as much as his coach wants him to, and at least help the team win the league. Leave Paris with a Ligue 1 trophy, Leo!
The remaining place is up for grabs for one of Hugo Ekitike and Carlos Soler. Ekitike has gotten the benefit of Galtier of late even on brief appearances here and there while Soler seems to have lost all of the trust of the French manager.
Soler played 90 minutes in the loss at Monaco, then 57 in the first-leg matchup against Bayern, but only 16 and 20 minutes against Lille and Nantes respectively. He had played a lot after the World Cup break starting a whole bunch of games, so I think Galtier will at least try to showcase him ahead of the summer just to see if somebody falls for the trap and attempts to sign him.