The Argentina international has returned to Paris after testing negative for COVID-19, although he has yet to be cleared to play.
While several had predicted a rift in their relationship, Pochettino confirmed that Messi had actually picked up a knee injury.
Neymar canceled out Lucas Pacqueta's opener before substitute Mauro Icardi scored an injury time winner for PSG against Lyon.
Maxwel Cornet, who can play on either wing or left-back, will join up with the squad following the international break.
Leicester City have been drawn to face Napoli in the Europa League group stage. The Foxes will also face Spartak Moscow and Legia Warsaw.
FC Barcelona and Memphis Depay have reached an agreement for the player to join the Spanish club, following the end of his contract with Olympique Lyonnais.
The French Ligue 1 capped an epic season this time around with an unlikely title winner, with LOSC Lille being crowned champions.
Top three teams Lille, PSG and Monaco can with the Ligue 1 title as they are separated by just three points going into the final match day