Put in to bat, Karnataka posted 242 for nine in their allotted 50 overs and then bundled out Haryana for 204 in 46.3 overs.
Karnataka rode on crucial contributions from opener KL Rahul (40), and tail-enders Jagadeesha Suchith (46) and skipper R Vinay Kumar (41) to get past the 240-run mark.
For Haryana, Harshal Patel was the pick of the bowlers with figures of four for 62.
Chasing a competitive total, Haryana got off to a disastrous start, losing their top three wickets for just 10 runs on the board.
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At the end, the visitors failed to cross the final hurdle with Abhimanyu Mithun (2/26), Vinay Kumar (2/39) and Suchith (2/40) chipping in with two wickets each.
Brief scores:
Karnataka: 242 for nine in 50 overs (Jagadeesha Suchith 46, R Vinay Kumar 41, KL Rahul 40; Harshal Patel 4/62).