England rediscovered their fight but still face a mountainous task to salvage a first-Test stalemate after collapsing to Indian spin on day three and having to follow on 330 runs behind.
Pragyan Ojha (five for 45) and Ravichandran Ashwin (three for 80) bowled England out for 191, yet neither of the Indian spinners could make any inroads in 28 more overs between them when the tourists tried again and succeeded to the tune of 111 for none.
Openers Alastair Cook (74) and Nick Compton (34) pulled together a partnership of significance at their second attempt, but it was still hard to argue with a consensus that they will probably lose an unequal struggle at some point over the next two days.
In reply to 521 for eight declared - England lost four wickets for 69 runs on Saturday morning and then, despite Matt Prior's 48, their last three by teatime. Prior responded to a critical situation with determination, interspersed with his instinct for counter-attacking strokeplay, but could not turn the tide.
Kevin Pietersen's comeback innings following his successful 'reintegration' was fretful throughout. He could easily have been out twice before adding to his overnight six, while Ojha knocked out his middle-stump.
Ian Bell was up the wicket to Ojha but an attempted lofted drive only ended in a golden duck - caught at deep mid-off. Cook crossed and survived the hat-trick ball ut soon afterwards Ashwin lured him into a drive and had him edging some spin low to slip, where Sehwag took a neat catch.
Prior was dropped on three after clubbing a full-toss from Ashwin to Zaheer Khan on the square-leg boundary. Samit Patel had no such luck. He got past the initial spin threat but was then lbw to one perhaps sliding towards leg when India finally introduced frontline seamer Umesh Yadav.
Prior and Tim Bresnan closed out the session, and began the next with promise in a stand of 47. But Bresnan, understandably playing low in defence, was undone by rare extra bounce as Ojha picked up his fourth wicket - caught at gully.
Stuart Broad announced himself by hitting Ojha over midwicket for four first ball; then when Ashwin returned, he took 13 of the 14 runs off his first over back, including a six over long-on from the crease.
But England's first-innings resistance was short-lived, Broad lbw to one from Zaheer, and then Prior missing an inside-out drive at Ojha. It seemed then that the tourists were on the fast track to defeat, until Cook and Compton revived hope that they could yet head for Mumbai next week 0-0 with three to play.