Switzerland have three 19-year-olds in their final European Championship squad of 23 players that features new Arsenal signing Granit Xhaka.
Coach Vladimir Petkovic was expected to pick Basel forward Breel Embolo, and on Monday also selected teenagers Nico Elvedi and Denis Zakaria.
Elvedi, a defender with Borussia Monchengladbach, and Young Boys midfielder Zakaria both made international debuts on Saturday in a 2-1 loss to Belgium in Geneva.
Zakaria takes a holding midfielder's place left vacant when Petkovic left out former captain Gokhan Inler over a lack of playing time at Leicester.
Petkovic also omitted defenders Philippe Senderos and Silvan Widmer, and midfielder Luca Zuffi, who had been on the provisional squad.
Switzerland's final warm-up friendly is against Moldova in Lugano on Friday.
The Swiss are in hosts France's group at Euro 2016 along with Albania and Romania.
The full squad:
Goalkeepers: Yann Sommer (Borussia Moenchengladbach), Roman Burki (Borussia Dortmund), Marwin Hitz (Augsburg)
Defenders: Stephan Lichtsteiner (Juventus), Nico Elvedi (Borussia Monchengladbach), Michael Lang (Basel), Johan Djourou (Hamburg), Steve von Bergen (Young Boys), Fabian Schaer (Hoffenheim), Francois Moubandje (Toulouse), Ricardo Rodriguez (Wolfsburg)
Midfielders: Valon Behrami (Watford), Blerim Dzemaili (Genoa), Gelson Fernandes (Rennes), Fabian Frei (Mainz), Granit Xhaka (Arsenal), Xherdan Shaqiri (Stoke), Denis Zakaria (Young Boys)
Forwards: Breel Embolo (Basel), Haris Seferovic (Eintracht Frankfurt), Admir Mehmedi (Bayer Leverkusen), Eren Derdiyok (Kasimpasa), Shani Tarashaj (Everton)