Shelton left Sunday's game early against the Rams with a pectoral inury, Dan Salomone of the Giants' official site reports.
Shelton left late in the game, so his absence creates little impact for now. He is the primary man behind Austin Johnson in the Giants' 3-4 defense, though, so any extended time missed would certainly leave the depth chart thin. Shelton will try to return in Week 7 against the Panthers.