Debutant Jan-Niklas Beste has suffered an adductor injury and will miss Germany's upcoming friendly internationals against France and the Netherlands.
The German Football Federation (DFB) said that Hoffenheim's Beste left the squad on Thursday.
Beste is the second from an original six players called up for the first time to miss the matches on Saturday in Lyon against France and on Tuesday in Frankfurt against the Dutch.
Bayern Munich's Alexander Pavlovic never joied the squad due to tonsillitis.
The other four are the VfB Stuttgart trio of Maximilian Mittelstädt, Deniz Undav and Waldemar Anton, plus Hoffenheim's Maximilian Beier. The squad also includes uncapped goalkeeper Oliver Baumann.
Beste's injury reduces Nagelsmann's squad to 23, after goalkeeper Manuel Neuer departed on Wednesday with an adductor injury.
