The Dortmund defender is suffering from a minor knee problem and may miss Germany's date in the showpiece final at the Maracana on Sunday.
The center back only played 45 minutes on Tuesday as Germany booked its place in the final with a stunning 7-1 victory over hosts Brazil, with the Dortmund man confirming after the match that the problem had been bothering him for a few days.
Coach Joachim Low opted to withdraw him at the break with Germany 5-0 ahead and cruising into Sunday's final, however, team manager Oliver Bierhoff still expects the defender to be involved and insisted Low had only substituted the 25-year-old as a precaution.
"Everyone's okay except for Mats Hummels and he's getting further treatment," Bierhoff told German TV station ARD. "It's a precautionary measure. We assume he'll be able to play in the final."
Hummels revealed he had been nursing the problem prior to the semifinal.
"I've had problems with it for a few days," he said. "But for the first time it didn't go away after warm-ups. In the match it got worse and worse.
"I made the decision that it's perhaps better to take myself out so that I wouldn't break anything.
"We'll have to see exactly what it is. It's not something tiny but fortunately I don't think it's anything that would endanger Sunday."