Root walked out to bat with England 0-1 after Ben Duckett was caught behind off Jasprit Bumrah from the first ball of the innings.
England were 8-2 when Jacob Bethell nicked a rising delivery from Prasidh Krishna to wicket-keeper Ishan Kishan, a replacement for the ill KL Rahul, before skipper Harry Brook fell to a skittish scoop.
Root, not for the first time in his long career, led an England revival as they chased down a modest target of 234 with 35 balls remaining to turn Sunday’s finale at Lord’s into a series decider.
The former England captain faced 133 balls, including nine fours, and was only denied what would have been his 21st ODI century when the recalled Gus Atkinson, riding his luck with a few streaky shots, pulled Prasidh Krishna for four.
When Sam Curran (22) was excellently taken standing up to the stumps by Kishan – the stand-in’s fourth catch – off Shivam Dube, England were faltering at 94-4.
But Root completed a 76-ball fifty – his second half-century in three days following his 76 not out in a six-wicket India win in Tuesday’s series opener at Edgbaston.
Fellow veteran Jos Buttler fell for just 17, clean bowled trying to drive left-arm spinner Axar Patel.
Root needed a reliable ally and it seemed he had found one in Will Jacks.
But having made 30, Jacks inexplicably backed away to leg and slapped paceman Gurnoor Brar straight to extra cover.
Root threw his head back in anguish as India gained renewed hope with England 197-6 off 40 overs.
Earlier, Jofra Archer led a much-improved England bowling display as India were dismissed for 233.
India looked set for a score in excess of 300 when Virat Kohli (65) and Shreyas Iyer (66) were at the crease together.
But a revamped England attack used the short ball to good effect to seize back the initiative at a sun-drenched Sophia Gardens.
India, who had been 178-3, lost their last seven wickets for 55 runs – including a mini collapse of 4-15 – as they were all out with six overs remaining.
Fast bowler Archer took 3-47 from his 10 overs after Brook won the toss, with Atkinson and Saqib Mahmood recalled to bolster England’s seam-bowling options.
India captain Shubman Gill, fresh from his 80 at Edgbaston, fell for 31 when he drove Atkinson to cover.
Kohli has already retired from Test and T20 international cricket and this series could be the last time the legendary 37-year-old represents India in Britain.
He showed his class by straight-driving Curran for four to bring up a run-a-ball fifty as chants of “Kohli, Kohli, Kohli” echoed round the ground.
Iyer was dropped on 25 and soon afterwards, he drove leg-spinner Adil Rashid for a soaring straight six.
England dismissed Kohli when a top edge off Archer flew to Rashid at third man.
Archer struck with successive deliveries to reduce India to 193-7.
Patel was caught behind off a attempted ramp and Dube drove a fuller-length delivery straight back to Archer.
Iyer’s casual hook for six off Archer saw him to a 42-ball fifty. But he fell tamely, caught behind off Atkinson, who finished with 3-50. (AFP)
