Unheralded Ramaswamy Prasanna scored his first century in five years before skipper Laxmipathy Balaji bowled a fiery opening spell to rip apart the Mumbai top-order as Tamil Nadu look firm favourites to enter the Ranji Trophy final.
At stumps on second day, Mumbai were tottering at 121 for 6 in reply to Tamil Nadu's healthy first innings score of 359 with only one specialist batsman left in Hiken Shah. Dhawal Kulkarni is other not-out batsman.
The left-handed Shah was unbeaten on 21 after a stay of 83 minutes while Kulkarni was not out on 5 as the 39-time national champions Mumbai still need 89 runs more to avoid follow-on.
When Mumbai began their reply, India discard Balaji blasted out openers Kaustubh Pawar (1), Onkar Gurav (2). Rival captain Wasim Jaffer (0) was out due to a dubious decision - in the space of six balls to reduce the home team to 14 for 3.
Balaji's superb first spell figures read 7-4-11-3.
The hosts recovered partially through their men in-form Abhishek Nayar (17) and highest scorer Suryakumar Yadav (52,57 balls, 8x4) before losing both of them as well as last match's centurion Ankit Chavan (10) before crossing the 100-run-mark.
On Thursday, Shah will have the big responsibility to lift the hosts from the brink on the morrow like Prasanna had done for Tamil Nadu when they were struggling at 139 for six soon after lunch on Tuesday.
Prasanna, who was unbeaten on 81 after guiding Tamil Nadu through troubled waters on Tuesday in the company of Vijaykumar Yo Mahesh (67) departed after making 104, his first ton since scoring 134 against Uttar Pradesh in December, 2006. The duo added 152 runs for the seventh wicket.
Prasanna was bowled through the gate in the 16th over of the day by Nayar after the 29-year-old had struck 17 fours in his 375-ball innings. This was Prasanna's third-class century.
Starting the day at 250 for 6, continued their fight back with Balaji joining the battle.
Yo Mahesh, who batted dourly for 363 minutes, struck two sixes and four fours in his 259-ball essay and was ninth out to Kshemal Waingankar. He put on another very handy 42 runs with Balaji (24) for the eighth wicket.
The last four wickets added a staggering 220 runs for Tamil Nadu.
Surprisingly Mumbai captain Jaffer did not employ attacking fields when Yo Mahesh and Prasanna were together against the second new ball which was only eight overs old in the morning.
Medium pacer Kshemal Waingankar was also under-utilised and was brought on only after an hour's play and secured one wicket while off spinner Ramesh Powar was also used sparingly and got a wicket off his second ball of the morning, the last over before lunch.
Sandhu ended up with impressive figures of five for 88, Kulkarni got 2 for 91 while Waingankar, Nayar and Powar got the remaining wickets.
Mumbai began their reply midway through the second session and were immediately rocked back on the back foot by Balaji who fired out Pawar and Gurav through catches behind the stumps and earned a leg before appeal off a big inside edge against Jaffer from umpire K Hariharan.