Undergoing rehabilitation at the NCA in Bangalore, Rohit Sharma and Ishant Sharma must leave for Australia in the next few days if they are to feature in the starting XI for the upcoming Test series in Australia, said head coach Ravi Shastri. 

Rohit and Ishant are recovering from their hamstring injury and side strain, respectively, at the moment. However, the 14-day quarantine regulation amid COVID-19 pandemic means they stand no chance of playing the first of two pre-series warm-up matches starting December 6. 

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Both the players can only take part in the second of those practise games, beginning December 10, for which also they'll need NCA approval and must reach Australia by November 26. 

The Test series begins on December 17 in Adelaide with India's maiden away pink-ball encounter under lights. 

"He (Rohit) was never going to play the white-ball series, they were just looking to see how long he needed the rest, because you can't afford to be resting for too long," Shastri told ABC Sport.

"If you need to play in the Test series or any red-ball cricket, you've got to be on the flight in the next three or four days. If you aren't, then it's going to be tough."

"But things could get difficult if he's asked to wait for too long, (because) then you're talking of the quarantine again, which might make it really tough for even him to come just in time for the Test series," he added. 

Earlier in an interview with PTI, Rohit mentioned that his hamstring is gaining strength and he is confident of making the Test trip on time. 

Ishant, being the most experienced of the Indian quicks, the team management doesn't want to take any risk with his injury and will want to see how he cops up in at least one practise game before going ahead with his Test series participation. 

"It's (Ishant's) a similar case to Rohit," Shastri said. "You don't really know how quickly he'll be available to fly out. Like I said, if anyone has to play in the Test series, he has to be on the flight in the next four or five days. Otherwise, it's very difficult."

Shastri, meanwhile, hailed India captain Virat Kohli as the "driving force" behind the team's progress and backed his decision to prioritise his family as he returns home on paternity leave after the first Test. 

"I think it's the right decision he's taking," Shastri said. "These moments don't come time and time again. He has the opportunity, he's going back, and I think he'll be happier for that."

"If you see where India have gone in the last five-six years, there's no doubt in absolutely anyone's mind that he's the driving force and the man behind it (India's success)."

"So he obviously would be missed. But like I say, in adversity comes opportunity. There are lot of young guys in the side and it's an opportunity for them," he added. 

(Inputs from PTI)