Joachim Low's men began their FIFA World Cup campaign with a crushing 4-0 Group G victory over 10-man Portugal last Monday.
However, Germany came out of that fixture with worries over Jerome Boateng (thumb) and Hummels.
Boateng has been able to train and should be fine to face Ghana on Saturday, but Hummels' inclusion remains in doubt with the Borussia Dortmund man doing individual training in a bid to be fit.
Should he not make it, one suggestion mooted was to switch Boateng to centre-back and move captain Lahm from a defensive midfield role to full-back.
Assistant coach Hansi Flick, however, suggested that was not an option being discussed.
"Philipp Lahm will stay in centre midfield even if Mats Hummels is unfit for Saturday," Flick said a press conference. "We have enough alternatives to this position."
On Boateng and Hummels, he added: "Jerome trained normally today, Mats trained individually and is treated throughout the day.
"We hope that our excellent medical department ensures that Mats is able to play on Saturday."
