Resuming the day at 26 for no loss, Karnataka ended the day at 239 for three in response to Chennai's mammoth 538 for four declared.
There will be a good contest between the ball and the bat on the final day although Chennai would start favourite to get the first innings lead since no team has scored more than 260 runs on a single day in this match.
It will be difficult for Karnataka to score 300 or more to get the first innings lead.
Robin Uthappa (53) and K B Pawan (69), who began the proceedings for the visitors, put on 94 runs in their opening stand.
Off-spinner Malolan Rangarajan broke the fighting stand when he trapped Uthappa, who faced 134 balls and hit six boundaries including one six.
Ganesh Satish joined Pawan in the middle and stayed till the end of the day with an unbeaten 65. But Karnataka lost Pawan and Manish Pandey (6) in between.
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Pawan was dismissed by Abhinav Mukund while Pandey became the second victim of Rangarajan.
Satish has so far faced 184 balls and helped himself with four shots to the fence.
Amit Verma supported Satish well from the other end and was unbeaten on 18.
Brief Scores:
Chennai 1st innings: 538/4 dec
Karnataka 1st innings: 239 for 3 in 100 overs. (G Satish 65 batting; K B Pawan 69; Malolan Rangarajan 2/67)