Messi had a nice game against Lyon on Sunday though is yet to score for his new side.
Having suffered a knock in Sunday's game, the Argentine forward will not be part of PSG's trip to Metz.
Confirming the situation of the former Barcelona man, PSG in a statement said;
"Lionel Messi, who took a knock to his left knee against Lyon, underwent an MRI on Tuesday morning which confirmed signs of bruising of the bone. A follow-up examination will be carried out in 48 hours."
PSG have won all their six Ligue 1 games this season and are keen on winning the league title after missing out on the ultimate to Lille last season.
The Parisians returned to winning ways following a disappointing result in their first Champions League game with Club Brugge.
With the quest for winning the Champions League for the first time, PSG have bolster their squad with marquee signings.
Messi was PSG's fourth free-transfer signing during the summer transfer window following the arrivals of former Liverpool midfielder Georginio Wijnaldum, Spain defender Sergio Ramos and Italy goalkeeper Gianluigi Donnarumma.
The six-time Ballon d'Or completed his shocking move to Paris Saint-Germain on a two-year deal with the option of extending for a further year after departing Barcelona.
Bringing to an end of a 21-year stay at Barcelona, Messi remains the club's record scorer with 672 goals and won 10 La Liga titles, four Champions Leagues, seven Copa del Rey trophies, including six Ballon d'Or glories.
