The Germany centre-back hobbled from the field during Monday's victory against Portugal, sparking fears he could miss the rest of the tournament
The centre-back scored his side's second goal of the game with a thumping header after Thomas Muller had given Joachim Low's men the lead.
The midfielder struck a further two times as Germany put 10-man Portugal to the sword following Pepe's red card, but Hummels' withdrawal in the second period prompted fears he could miss the rest of the tournament.
"I have been struck on the thigh," Hummels said after the game.
"That's why a replacement came on. There's always a worry that the injury could be worse than first thought but with a bit of luck I will be fine in just a few days."
Injuries have blighted Germany's build-up to the tournament, with Sami Khedira and Bastian Schweinsteiger overcoming problems, while Holger Badstuber was ruled out before the competition began.
Ghana will be Germany's next Group G opponents, on Saturday evening in Fortaleza.