The hosts are yet to announce their playing XI but Peter Handscomb's middle order position looked in jeopardy after Langer backed Marsh who missed the first two tests of the four-match series currently level at 1-1.
"In a perfectly balanced side, you've got someone who can bowl some overs," Langer told reporters on Monday.
"And Mitch becomes an attractive commodity on a wicket unlike Adelaide and Perth... although there's a bit of moisture in it, we also know the history of it."
Number five Handscomb has managed 68 runs in four innings against India.
Forecast for warm weather and only three days' gap before the final test in Sydney also means Australia would be extra careful about managing the workload of their frontline pacemen.
"Our fast bowlers have been lucky, we've bowled less overs than India's bowlers at the moment, particularly (Jasprit) Bumrah, and that's an important part of the series," Langer said. "We're always looking at how we're trying to manage it.
"In this instance, this is the only test we're thinking about. But we're always aware that there's two back-to-back test matches, which is tough."
Langer joked the selection dilemma had taken his mind off everything else.
"Pete's a very good player of spin bowling... and Mitch is a pretty good player of spin bowling too," he said.
"We'll weigh up all those things, and they're the hard decisions. All those factors, trust me, we think about it.
"It's a bit sad, really; I'm not thinking about what Christmas present I'm going to give to my kids, I'm thinking about who plays spin better, whether we'll play the extra bowler, how many overs have the fast bowlers bowled. It's sad."
Langer also said he could not wait to welcome Steve Smith back in the side once the former captain has served out his ball-tampering ban, which ends in March.
"We can't wait to have him back. He's the Virat Kohli of the Australian cricket team," Langer said, likening the 29-year-old to India's talismanic captain and batting mainstay.
(Reporting by Amlan Chakraborty in New Delhi; editing by Sudipto Ganguly)
