The hosts approached their last ODI series before this year's World Cup more as an assessment of their preparedness for the showpiece event in England and Wales.
With Hardik Pandya, India's first choice pace-bowling all-rounder, recovering from a back injury, Shankar capitalised on his opportunity against Australia to catapult himself into World Cup contentions with some impressive performances.
The 28-year-old has proved he can float in the batting order and, with the ball, can hold his nerve in the death overs.
"Vijay has gained in confidence. He's batted brilliantly at any given position given to him," India's bowling coach Bharat Arun told reporters at Feroz Shah Kotla ahead of the fifth and final match of the series, currently level at 2-2.
"He batted at number four, six and seven, and he has done exceptionally well."
He has been equally impressive with the ball.
Barely two months after his ODI debut in Melbourne, Shankar was at the thick of things in the second match against Australia when he was entrusted with the last over with the tourists needing 11 from it with two wickets in hand.
The right-arm seamer, who had contributed a breezy 46 with the bat at number five, responded by dismissing the in-form Marcus Stoinis and Adam Zampa in the space of three deliveries to secure India's narrow win.
"The confidence he has gained with his bating is rubbing onto his bowling as well," Arun said.
"The way he started, he was bowling at 120-125 (kph). Now he is touching 130s. He looks a lot more confident in his bowling. So yes, Vijay Shankar has been a huge positive for the team."
Arun would not disclose if Shankar was being considered at the number four position, a place captain Virat Kohli filled in the fourth ODI in Mohali.
"Those are not necessarily the combinations which will be in World Cup but we would like to know how people perform in different situations for us to pick up a balanced team for the World Cup," Arun said.
"We'll be extremely sure (of) what we want before going into a major tournament like World Cup."
(Reporting by Amlan Chakraborty in New Delhi; editing by Sudipto Ganguly)
