Hummels is one of several players, including Manuel Neuer, Thomas Mueller, Mesut Ozil and Toni Kroos - all 2014 World Cup winners - who have returned for their qualifiers against the Czech Republic on Friday and Norway three days later.
Coach Joachim Loew had rested them in the summer ahead of next year's 2018 World Cup in Russia.
"Yes, we have to (prove ourselves) a little bit," Hummels told reporters. "But it is not a bad thing. It was the same some years ago when we, the then (2009) Under-21 European champions, put pressure on those in the national team.
"This helps that everyone is at 100 percent, because there is not one but three or four talented players waiting in the wings. It does not make us weaker but stronger."
There are other world champions, including Jerome Boateng, Manuel Neuer and Sami Khedira, who have yet to return but will want to earn their starting spot back once fit.
Germany top Group C on 18 points, five off second-placed Northern Ireland and nine ahead of the Czechs, who are third.
Loew has included 17 players from his Confed Cup squad and warned his big names would have to deliver.
"There is no player who has a free ticket for the World Cup," Loew said. "They have to deliver good performances, they have to know what their goals for the season are."
Loew's team could wrap up qualification with a win against Norway in combination with other results.
"The more players in top form next year, the higher chances of winning the title," Loew said.
"The past counts for nothing in football. You have to invest to be ready next year. I told my players that. The Confed Cup made our choice of players bigger. But the final decision will not be taken now but much later."
Loew confirmed Hummels, Mueller, Kroos, Ozil, Joshua Kimmich, Jonas Hector and keeper Marc-Andre ter Stegen would be in the lineup.
"The Czechs are with their backs to the wall and against us they have to get points, and win against Northern Ireland. Otherwise their World Cup dream is over," he said.
(Reporting by Karolos Grohmann in Berlin; editing by Mark Heinrich)
