Borussia Dortmund boss Jurgen Klopp confirmed regular custodian Weidenfeller is battling a groin injury he sustained in the midweek DFB Pokal semi-final win over Wolfsburg.
"It looks like Weidenfeller won’t be able to play, which means Langerak will likely play," Klopp told reporters on Thursday.
Klopp failed to confirm the extent of the injury, but Weidenfeller managed to play out the semi-final, which booked Dortmund’s spot in the decider against Bayern Munich, suggesting it isn’t too serious.
Dortmund still have four league matches and the DFB Pokal final to play, before the conclusion of their season.
Langerak appears behind Club Brugge stopper Mat Ryan in the race to be Australia’s preferred keeper in Brazil due to a lack of regular game-time and after being sent off in last month's 4-3 friendly loss to Ecuador.
The 25-year-old has made nine Bundesliga appearances for Dortmund in his time at the club, including two this season. He has never been on a losing Dortmund side in the league.
Earlier this month, the former Melbourne Victory man stepped up when Weidenfeller was absent with a hand injury. Dortmund defeated Wolfsburg 2-1 on that day.
Langerak has made seven appearances in all competitions for the German giants this term.
He was dismissed in Australia’s friendly loss to Ecuador last month, when he came off the bench as a half-time substitute with the side leading 3-0.