Neither Klostermann nor Hofmann were involved in Tuesday's 1-0 defeat by world champions France in Germany's opening game, but Gnabry started and returned to training Friday after being given a day's rest.
Borussia Moenchengladbach's Hofmann is struggling to shake off a knee injury picked up before the tournament and is not in contention for Saturday's Group F match at the Allianz Arena. RB Leipzig right-back Klostermann is sidelined by a hamstring strain.
His injury settles the debate who should start at right-back against Portugal, with Bayern Munich midfielder Joshua Kimmich set to again be named on the right flank. Kimmich, now a central midfielder for his club, has been moved back into defence for the European Championship, but with Klostermann sidelined, coach Joachim Loew now has no other option at right-back.
A win for Portugal in Munich would put the holders through to the last 16, while Germany are still looking for their first points.