Electing to bat, Delhi rode on skipper Mithun Manhas's 97 and Aakash Chopra's 85 to put up a challenging 291 in 50 overs. Shikhar Dhawan also chipped in with a useful 46.
Manhas' innings was studded with 12 boundaries. Chopra hit seven fours beside two sixes. For Haryana, Yoginder Singh took three wickets for 64 runs.
Chasing a stiff target, Haryana were bowled out for 255 in the penultimate over. Sumit Sharma (82) and Shafiq Khan (70) tried to make a match of it but could not pull their side through. Sunny Singh also made a quickfire 39 in 40 balls.
Super-sub Kunnal Lall shone with ball taking four wickets while rookie bowler Ishant Sharma claimed three for 44.
Delhi now have 8 points while Haryana have 9 points after four matches.
In a nail-biting finish, zonal favourites Punjab went down by two runs to Services.
Punjab, who has won their three previous matches, needed five runs in the last over but they lost their last two wickets handing four points to Services.
Electing to bat, Services were all out for 261 runs in 49.1 overs with Sumit Tomar (103) being the chief contributor. Yashpal Singh made 71 with 10 fours. Harminder Singh claimed five wickets for 50 runs.
For Punjab, Pankaj Dharmani scored 61 while Ravneet Ricky made 45. It was the debutant off-spinner Rajesh Sharma who did the damage with figures of 5-28. Skipper Dinesh Mongia also took two wickets. With three runs needed from the last ball Arminder Singh was caught behind off Rajesh. Punjab now have 13 points while Services have eight.
In another match, Himachal Pradesh scored a 48-run win over Jammu and Kashmir.
Put in to bat, Himachal Pradesh rode on Sandeep Sharma's century to score 260 for 9 in 50 overs. Skipper Nischal Gaur made 61.
In response, Jammu and Kashmir were all out for 212 in 44.4 overs. Kawaljit Singh's 84 and Arshad Bhat's 53 went in vain. Nischal took two wickets for 41 runs.
Himachal Pradesh have 13 points with J-K still to open their account.