Their knocks helped Andhra wrest the initiative against the star-studded hosts after having been 64 for 5 at one point to end the day at 231 for 7, a lead of 55.
Tamil Nadu had been dismissed for 176 in the first innings yesterday.
Resuming at the overnight score of eight without loss, the visiting side was in trouble almost immediately as opener D B Prashanth Kumar fell to L Vignesh.
Vignesh got one to move away from the batsman Prashanth to have him caught at second slip by B Indrajith.
Skipper Hanuma Vihari was the next to depart, falling to a catch by BN Aparajith at gully off the bowling of L Vignesh for 3.
K S Bharat and Ricky Bhui began the rescue act but after adding 28 runs before the latter was dismissed by the other Vignesh.
The experienced Y Venugopala Rao didn't last too long as he was caught by Rahil Shah off R Ashwin's bowling for just three.
When Ashwin had Bharat stumped by N Jagadeesan for 32, Andhra looked in trouble at 64 for 5.
The TN bowlers had done very well till that point and fielders had played their part too, taking the catches came their way.
Then came a vital moment in the game as M S Washington Sundar dropped Ashwin Hebbar off Ashwin's bowling at deep mid-wicket.
The 21-year-old batsman made the most of the life he got and scored runs in an attractive manner.
From 95 for 5 at lunch, Sumanth, who showed great resolve to defy the bowling, took the fight to Tamil Nadu in Hebbar's company.
Sumanth didn't resume his knock after the tea interval owing to a hand injury, but Hebbar kept the scoreboard moving. Shoaib Mohammed Khan provided valuable support and they took the total to 182 before Hebbar's knock ended. He was dismissed by K Vignesh for 64.
Bhargav Bhatt, the team's bowling hero yesterday, was caught behind off Washington Sundar's bowling.
Sumanth, who returned at the fall of Bhatt, took the team to the close without any further damage and swelled the lead to 55 runs.
For Tamil Nadu, K Vignesh, L Vignesh and Ashwin bagged two wickets each.
Test all-rounder Ashwin, who bowled 23 overs, looked dangerous in the first session but couldn't make much of an impression in the post-lunch period.
At the end of the day, Tamil Nadu coach Hrishikesh Kanitkar said the Andhra batsmen played very well and the drop by Washington Sundar did make a difference.
"I think credit is due to them for the way they batted. I think it could have (the dropped chance of Hebbar) made a difference. Catches being dropped are part of the game and I wouldn't dwell much on it," he told reporters.
Scores: (End of day 2):
Tamil Nadu 176 all out (Baba Aparajith 51, K Vignesh 25 not out, Bhargav Bhatt 4 for 52, Prithvi Raj Yarra 3 for 39) vs Andhra Pradesh 231 for 7 (B Sumanth 72 batting, Ashwin Hebbar 64, K S Bharat 32, K Vignesh 2 for 46, L Vignesh 2 for 36, R Ashwin 2 for 51) in Chennai.
Madhya Pradesh 551 for 8 declared in 164 overs (Devendra Bundela 99, Shubam Sharma 196, Ankit Sharma 104, Harpreet Singh Bhatia 32, A Sheth 2 for 90, Swapnil K Singh 3 for 136) vs Baroda 36 for 2 in 13 overs (Kedar Devdhar 20 batting) at Indore.
Tripura vs Odisha - Play on day two also washed out without a ball being bowled, at Cuttack.
First Published: October 7, 2017, 8:54 PM IST