Debutant spinner Tom Hartley took seven wickets as England pulled off a dramatic 28-run upset win over India marked by a stellar batting performance by Ollie Pope in the opening Test on Sunday.
"Since I've taken the captaincy on... it's 100 percent our greatest victory," England skipper Ben Stokes said.
Chasing 231 for victory, India were bowled out for 202 in the final over of an extended third session of play on the fourth day in Hyderabad, as Hartley got Mohammed Siraj stumped with his left-arm spin to trigger celebrations from the England camp.
Pope stood out with his 196 to bring England bouncing back from being 190 behind at the start of their second innings to lead the five-match series 1-0.
"To come here to India, toughest place as a batter and put in a winning performance, it's head and shoulders above the rest," Pope said after being named man of the match in his comeback Test, after suffering a shoulder injury last year.
Hartley, who got his five-wicket haul after he bowled wicketkeeper-batsman K.S. Bharat, returned innings figures of 7-62 and had a match tally of nine wickets.
"It's unbelievable," Hartley said after the match, adding that the win was "not going to sink in" for some time. "I'm over the moon."
India came into the high-profile encounter as favourites on home soil, with an unbeaten Test series record since 2012, when Alastair Cook's England beat them 2-1.
Indian skipper Rohit Sharma said it was "hard to pinpoint where it went wrong", and congratulated England for "exceptional" batting.
"You've got to take your hat off, and say 'well played' to Pope," he said.