Speaking with media on Friday, Nagelsmann said Germany "want to have a clear core of players who form the foundation for the World Cup".
After going out in the quarter-finals of the Euros to eventual champions Spain on home soil in July, Germany have lost several experienced players.
Toni Kroos, Manuel Neuer and Thomas Muller, all 2014 World Cup winners, have retired from international football, as has Ilkay Gundogan, who captained the hosts at Euro 2024.
The coach said he "did not have any withdrawal symptoms" after the loss of the decorated quartet and backed his changed squad.
"We'll have a different starting XI but not a completely different squad. This group knows itself well, even if there's a few new players around."
The coach revealed Pascal Gross would take Kroos' spot in defensive midfield, while forwards Kai Havertz and Niclas Fullkrug would both play in a bid to recreate Gundogan's lost creativity.
"Pascal will play. He's not 'doing the Kroos', he's 'doing the Pascal'. We are not looking to replace Toni Kroos, we're looking for someone who brings their own skills."
In his press conference after the extra-time loss to Spain in Stuttgart in July, Nagelsmann said his goal was to "win the World Cup" in two years, which will be hosted jointly by the United States, Canada and Mexico.
On Friday, he hit back at criticism of the statement.
"I think we should set big goals and let people know. I was criticised for saying I want to win the World Cup, which I find crazy."
When Nagelsmann asked Gross who was sitting alongside him if he was putting him under pressure by saying that, the Borussia Dortmund midfielder shook his head in denial.
"The first game after the Euros is very important in order to get the fans onside, to take them with us and build momentum for the next two years.
"We want to have the same enthusiasm and desire to win that we had at the Euros."
Germany beat Hungary 2-0 in Stuttgart during the group phase of the Euros but Nagelsmann said that they "can expect a different opponent" on Saturday.
