Back in the side after missing the semifinal due to a groin strain, Kulkarni utilised the green track on offer to perfection after Mumbai skipper Aditya Tare won the toss and invited Saurashtra to bat.
Kulkarni was spot on with his line and length, and managed to cut through Saurashtra top-order with figures of four for 30, which included the important wickets of opener Avi Barot, Cheteshwar Pujara, Arpit Vasavada and skipper Jaydev Shah.
Kulkarni, in particular, produced an impressive opening spell as Mumbai reduced Saurashtra to 108 for seven at one stage.
Had it not been for Arpit Vasavada and debutant Prerak Mankad, it could have been an embarrassing scorecard for Saurashtra at the end of day's play during which they played 84.4 overs.
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Vasavada (77) played a patient knock and held one end together during his 214-ball stay at the crease, which included just six boundaries, even as the wickets kept tumbling at the other end.
However, Vasavada was the last wicket to fall when he became Kulkarni's fourth victim of the day.
For records, Saurashtra have never beaten Mumbai in 53 previous attempts. This is the first time both sides are playing at a neutral venue.