After bundling out Kerala for 225, Saurashtra struggled to post 232 before their first innings folded.
At stumps, Kerala were 69 for one in their second innings with Jalaj Saxena unbeaten on 29 and Rohan Prem on 27.
Resuming on 37 for no loss, overnight batsman Uthappa, starting on 20, went on to score 86 off 120 deliveries studded with 10 boundaries and five sixes.
Uthappa's partner Snell Patel added 33 runs to his last night's score of 16 before falling for a 78-ball 49, including eight fours. The two added 107 runs for the opening wicket.
After Patel's departure, Uthappa continued to score runs in the company of Avi Barot (7).
But Barot's dismissal triggered a collapse and Saurashtra lost six wickets for just an addition of 34 runs.
Lower down the order, Jay Chauhan (30 not out) and Jaydev Unadkat (26) steadied the boat, putting on 45 runs to take the Saurashtra's score past 220-run mark.
Eventually Saurashtra could take only seven-run lead. For Kerala, Sijomon Joseph finished with figures of four for 43 while Basil Thampi chipped in with three for 36.
Kerala: 225 & 69/1 in 19 overs Saurashtra 1st innings: 232 all out in 78.5 overs (Robin Uthappa 86, Snell Patel 49; Sijomon Joseph 4/43, Basil Thampi 3/36).
Brief scores of other Group B matches:
At Surat: Rajasthan 1st innings: 153 Gujarat 1st innings: 450 for three (Priyank Panchal 152, Parthiv Patel 119 batting, Bhargav Merai 110).
Haryana 1st innings: 184 (Amit Mishra 41, Himanshu Rana 35; Ram Dayal 5/57, Mohammed Mudhasir 4/56). J&K 1st innings: 175 for 7 in 53 overs (Ahmed Bandy 67).
First Published: November 18, 2017, 10:13 PM IST