Earlier, Punjab,riding on under-19 World Cup star Shubman Gill's brilliant unbeaten knock of 123 made 269 for 3 in 42 overs in a game reduced after a delayed start owing to a wet outfield.
The right-hander hit eight fours and six sixers in his 122-ball innings and put on 125 runs for the second wicket with Mandeep Singh (64).
In reply, the home side looked in control as long the stylish Rahul was at the crease.
He was also involved in an even 100-run partnership with Pavan Deshpande (53).
However, the exit of Deshpande pegged Karnataka back.
Rahul fell with 21 runs to go but skipper Vinay Kumar's 26 couldn't take the team over the line.
Karnataka continues to top the table with 10 points from four games, while Railways, Punjab, Odisha and Baroda have eight points each.
Railways, Odisha and Baroda have played three games while Karnataka and Punjab have played four matches each.
In other matches, Odisha thrashed Assam by nine wickets as Rajesh Dhuper (70 not out) and skipper Govinda Poddar (50 not out) reached the target of 137 in 25.4 overs and Railways posted a 51-run win thanks to an solid batting effort by the top-order.
Points: Odisha: 4; Assam: 0.
At Alur: Punjab 269 for 3 in 42 overs (Shubnam Gill 123 not out, Mandeep Singh 64) beat Karnataka 264 for 9 in 42 overs (K L Rahul 107,Pavan Deshpande 53, Vinay Kumar 26 not out, Siddharth Kaul 3 for 47).
Points: Punjab: 4; Karnataka: 0.
Railways 272 for 7 in 50 overs (Mrunal Devdhar 68, Saurabh Wakaskar 58, Arindam Ghosh 55, H V Patel 3 for 62) beat Haryana 221 all out in 45.1 overs (C K Bishnoi 79, RP Sharma 50, Ankit Yadav 4 for 36).
Points: Railways: 4; Haryana: 0.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)