Borussia Dortmund's Hummels recalled in Nagelsmann's first Germany squad
Nagelsmann was appointed to the role last month in place of Hansi Flick, who left Germany after their 4-1 home loss to Japan in a friendly match, which followed several months of mediocre performances from the four-time world champions.
Borussia Dortmund defender Hummels, a 2014 World Cup winner, returns to the squad for the first time since he played 90 minutes in Germany's last 16 defeat by England at the European Championship in 2021.
Bayern Munich midfielder Thomas Muller, restored to the squad for games against Japan and France last month, retains his spot while Bayer Leverkusen's Robert Andrich, Union Berlin's Kevin Behrens and Stuttgart's Chris Fuhrich have been called up for the first time.
Germany take on the United States in Connecticut on October 14, before facing Mexico in Philadelphia on October 17, where they will be looking to build momentum ahead of next year's European Championship on home soil.
Squad:
Goalkeepers: Marc-Andre ter Stegen (Barcelona), Kevin Trapp (Eintracht Frankfurt), Bernd Leno (Fulham), Oliver Baumann (Hoffenheim)
Defenders: Antonio Rudiger (Real Madrid), Malick Thiaw (AC Milan), Jonathan Tah (Bayer Leverkusen), Mats Hummels (Borussia Dortmund), Niklas Sule (Borussia Dortmund), David Raum (RB Leipzig), Robin Gosens (Union Berlin)
Midfielders: Joshua Kimmich (Bayern Munich), Leon Goretzka (Bayern Munich), Florian Wirtz (Bayer Leverkusen), Julian Brandt (Borussia Dortmund), Jamal Musiala (Bayern Munich), Pascal Gross (Brighton), Jonas Hofmann (Bayer Leverkusen), Leroy Sane (Bayern Munich), Ilkay Gundogan (Barcelona), Robert Andrich (Bayer Leverkusen), Chris Fuhrich (VfB Stuttgart)
Forwards: Kai Havertz (Arsenal), Niclas Fullkrug (Borussia Dortmund), Thomas Muller (Bayern Munich), Kevin Behrens (Union Berlin)