McGain will not play in the Australians' final tour match against a Board President's XI starting in Hyderabad on Thursday and is also in doubt for the second Test.
Tim Nielsen, Australia's coach, confirmed McGain would be assessed over the next 24 hours. "With the selectors coming in on the second day of this game, we will then be in the best situation to take a decision as to whether to ask for a replacement," he said. "This is a great opportunity for Jason Krejza."
Tasmania off-spinner Jason Krejza the leading candidate to make his Test debut in Bangalore replacing McGain.