Bayern Munich's German internationals led by national team captain Joshua Kimmich started the pre-season on Monday with diagnostics together with other World Cup players.
The players are then to join the squad of coach Vincent Kompany at a training camp in Bavaria which also started on Monday and precedes a trip to South Korea and Hong Kong from Saturday onwards.
Kimmich, Manuel Neuer, Aleksandar Pavlovic, Jonathan Tah and Jonas Urbig rejoined the domestic double winners Bayern almost a month after Germany's last 32 exit against Paraguay at the World Cup.
The Bild paper said that Japan's Hiroki Ito, Kim Minjae of South Korea, Canada captain Alphonso Davies and Senegal teenager Bara Ndiaye are also back from representing their countries.
Midfielder Ndiaye, 18, is to receive a full contract after an initial loan from Gambinos Stars Africa and take the place of departed Leon Goretzka in the squad. Ndiaye has played four Bundesliga matches.
Also at the camp in Rottach-Egern is Germany full back Nathaniel Brown who has joined Bayern from Eintracht Frankfurt for €50 million ($56.9 million).
Konrad Laimer of Austria, Colombia's Luis Díaz and Croatian Josip Stanisic are to join the team for the August 1-8 trip to Asia.
England captain Harry Kane and France duo of Michael Olise and Dayot Upamecano will return only after that trip, the trio having contested the World Cup third place match just over a week ago. So will Germany player Jamal Musiala who had metal plate removed from his ankle after the World Cup.
Bayern start the season with the German Super Cup match against Borussia Dortmund on August 22 and their Bundesliga opener is six days later against VfB Stuttgart.