Opting to bowl, Delhi restricted Services to 131 for seven in the stipulated 20 overs and then, riding on Dhawan's blitzkrieg, chased down the target of 132 off with as many as 39 balls to spare at the Himachal Pradesh Cricket Association Stadium.
Dhawan's match-winning knock came a day after another southpaw, Gautam Gambhir, found his mojo back with a half century.
Such was the India player's onslaught that the failure of other Delhi players such as Unmukt Chand and Pawan Negi didn't matter.
After his 60-run knock yesterday, Gambhir got out for 11, but there was no stopping Dhawan as he carted the Services bowlers.
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For Services, Amit Pachhara top-scored with 56 off 46 deliveries, while Vikas Tokas (3/23) and Manan Sharma (2/8) were the most successful bowlers for the winning team.
In the day's other north zone match, Punjab defeated Himachal Pradesh by 23 runs.
Sent into bat, Punjab rode on opener Manan Vohra's 60 to post 162 for seven, and then restricted HP to 139 for nine.