Root's patient ton helps England to 302-7 after early wickets
England, who are fighting to stay alive at 2-1 down in the five-match series, reached stumps at 302-7 after electing to bat first in Ranchi.
Joe Root hit an unbeaten 106 to lead England's recovery from early trouble after Indian fast bowler Akash Deep took three wickets on debut in the fourth Test on Friday.
England, who are fighting to stay alive at 2-1 down in the five-match series, reached stumps at 302-7 after electing to bat first in Ranchi.
The tourists slipped to 112-5 but Root, with just 77 runs over his previous six innings, found his form to put on a 113-run stand with wicketkeeper-batsman Ben Foakes, who made 47.
Mohammed Siraj broke the partnership with the wicket of Foakes but former captain Root stood firm and had Ollie Robinson, on 31, for company in an unbeaten stand of 57 at the close of play.
Root's 31st Test ton came after a torrent of criticism for throwing away his wicket off a reverse scoop as England lost the third Test.
The veteran batsman reached his hundred with a boundary off Deep and then took off his helmet and raised his bat to a standing ovation from the England players and fans.
Root and Foakes kept calm in an uncharacteristically patient show of batting by England, a temporary departure from their attacking "Bazball" style, which denied India a wicket in the afternoon session.
Siraj was brought back into the attack after tea and the pace spearhead swung the ball to get Foakes caught at mid-wicket before bowling Tom Hartley for 13.
Root ploughed on with just nine boundaries in his 226-ball stay to give his team a much-needed boost on a cracked pitch expected to turn more.
The 27-year-old Deep shone as a replacement for Jasprit Bumrah, who has been rested, and had a scintillating start after getting his first Test cap from coach Rahul Dravid.
Deep thought he had got opener Zak Crawley on four only to overstep the crease for a no-ball.
Crawley, who went on to make 42, counter-attacked and hammered Siraj for four straight boundaries, including three fours and a six.
Deep got his first international wicket when Ben Duckett was caught behind for 11.
He struck again two balls later to trap Ollie Pope lbw for a duck, a decision denied by the on-field umpire but successfully reviewed by India after the tracker showed the ball would have hit the top of leg stump.
Deep then bowled Crawley with another beauty that darted in to the opener and rattled the stumps, as England slipped to 57-3 in only the first hour of play.
Root and Jonny Bairstow put together 52 runs before Ravichandran Ashwin had Bairstow lbw on 38 in another successful Indian review.
Skipper Ben Stokes was trapped lbw by Ravindra Jadeja for three on the stroke of lunch to leave England in serious trouble.