Sent in to bat, Delhi rode on Nitish Rana (66 off 34) and Hiten Dalal’s (49 off 41) impressive batting to post a challenging 182 for four.
Beside the duo, wicketkeeper Anuj Rawat made an unbeaten 34 while Lalit Yadav scored 23. India international Shikhar Dhawan failed to open his account.
Chasing the target, wicketkeeper Rohit Sharma made an unbeaten 48 and was ably supported by Chaitanya Bishnoi (35), Shivam Chauhan (32) and Rahul Tewatia (31 not out) as Haryana overhauled the target in 18.2 overs.
For Delhi, Lalit Yadav (3/38) and Simranjeet Singh (2/22) were the most successful bowlers.
By virtue of this win, Haryana are atop the standings in Group E with 12 points from three wins, while Delhi are placed third with eight points.
In another Group E match earlier in the day, Andhra dished out an all-round show to beat an in-form Kerala by six wickets.
Kerala, who had won their first three matches in the Elite E group, managed to score 112/4 after being asked to bat first at the BKC ground as the Andhra bowlers bowled in the right areas.
Andhra then overhauled the target in 17.1 overs, with opener Ashwin Hebbar top-scoring with a 46-ball 48.
Kerala lost both openers, Robin Uthhapa (8) and Mohammed Azharuddeen (12) cheaply and were in a spot of bother at 28/2. It soon became 30/3 after skipper Sanju Samson (7) also perished early.
Vishnu Vinod (4), who walked in at number five, gave little support to Sachin Baby (51 not out off 34 balls, 1×4; 4×6) as Kerala reeled at 38 for 4.
But then, Baby found an able partner in Jalaj Saxena (27 not out off 34 balls; 1×4) as the two forged an unbeaten 74-run stand for the fifth wicket to take their side to 112/4, which was eventually not enough.
For Andhra, Manish Golamaru (2/19) was the pick of the bowlers.
Andhra’s chase was anchored by right-handed opener Hebbar, who hammered six boundaries and a six, despite losing partners at the other end.
After Hebbar departed, skipper Ambati Rayudu (38 not out off 27 balls; 4×4 and 1×6) ensured that there were no further hiccups and took his side home in company of D B Prashanth Kumar (9 not out).
Andhra fetched four points for the win.
At BKC: Kerala 112/4 (Sachin Baby 51 not out; Jalaj Saxena 27 not out; Manish Golamaru 2/19, Shoiab Mohammed Khan 1/12) lost to Andhra Pradesh 113/4 (Ashwin Hebbar 48, Ambati Rayudu 38 not out; Jalaj Saxena 2/9) by six wickets.
At Wankhede Stadium: Mumbai 94 all out (Shivam Dube 28, Akash Parkar 20 not out; Santha Moorthy 5/20, A Aravinddaraj 2/20) lost to Puducherry 95/4 (S Karthik 26, Sheldon Jackson 24 not out; Shivam Dube 2/8) by six wickets.
At Wankhede Stadium: Delhi 182 for 4 in 20 overs (Nitish Rana 66, Hiten Dalal 49; Rahul Tewatia 1/20) lost to Haryana 183 for 5 in 18.2 overs (Rohit Sharma 48 not out, Chaitanya Bishnoi 35; Lalit Yadav 3/38) by 5 wickets.