England were 251-4 at stumps, with Root coming in when they were faltering at 44-2 after paceman Nitish Kumar Reddy struck twice in his first over to remove openers Ben Duckett and Zak Crawley.
Not for the first time in his 156 Test-career, the 34-year-old Root dug England out of a hole, at a run-rate of just above three an over well below the current ‘Bazball’ side’s usual standards.
England captain Ben Stokes, who won the toss at a sun-drenched Lord’s, was 39 not out after helping Root, his predecessor as skipper, add an unbroken 79 for the fifth wicket.
Stokes appeared to tweak his groin before the close, a worrying sign for England given his responsibilities as an all-rounder and one with potential implications for the workload of fast bowler Jofra Archer, recalled for this match after more than four years of injury-induced Test exile.
Root earlier shared a grinding partnership of 109 in 35 overs with Ollie Pope, who made 44 after almost being out for a golden duck.
“It’s not always been the way we’ve gone about our cricket, but I think long term in the game hopefully that will reward us if we can kick on tomorrow,” Pope told Sky Sports.
Much of the pre-match talk had focused on the return of Jasprit Bumrah, the world’s top-ranked Test bowler, after he was rested for India’s 336-run thrashing of England at Edgbaston last week that levelled the five-match series at 1-1.
Yet it was Reddy, the fourth seamer deployed by India captain Shubman Gill on Thursday, who struck twice in four balls on the way to figures of 2-46 in 14 overs.
With his third ball, the 22-year-old had left-hander Duckett well caught down the legside by diving wicketkeeper Rishabh Pant off a gloved pull.
Next ball, the often skittish Pope almost fell for a duck when he threw his bat at an outswinger, with Gill unable to hold a tough, low chance in the gully.
With the last ball of the over, Reddy produced a superb full-length delivery that swung late and straightened before taking Crawley’s outside edge to give Pant a simple catch as the Kent batsman fell for 18. (AFP)