Saurashtra skipper Jaydev Shah won the toss and decided to bat but opener Sagar Jogiyani exited early, making only 9 runs.
However, Kotak (46 runs, 132 balls, 5X4) and Cheteshwar Pujara (37 runs, 49 balls, 7X4) steadied the hosts' innings.
After the hosts lost both the set batsmen in a quick succession, Jackson and Vasavada added 93 runs for the fifth wicket, before Jackson's 128 balls inning was brought to an end by left-arm spinner KP Appanna.
Jackson made 83, hitting 12 fours and a six. Vasavada was batting on 49 and Chirag Jani is on 13 when stumps were drawn.
For Karnataka, Abhimanyu Mithun got two wickets conceding 47 runs while S Shivalingaiah, Appanna and K Gautam had a wicket each.
Brief Score: Saurashtra 272 for 5 (Sheldon Jackson, Sitanshu Kotak 46, Arpit Vasavada batting 49, Abhimanyu Mithun 2-47) against Karnataka.
