Wasim Khan took a hat-trick for Sussex seconds as they skittled Surrey out for 173 before rain ruined the Aon Trophy clash at Sutton.
Occasional medium-pacer Khan was introduced as Sussex's sixth bowler, and finished with 5-38 from his ten overs as Surrey were dismissed in 49.4 overs.
Sussex were unfortunate not to be able to follow up on Khan's good work as persistent rain after the lunch interval prevented them from starting their innings.
Khan's first hat-trick victim was Phil Sampson, who he had caught at long off by Will House for 21.
Scott Newman was then taken at backward point by Bas Zuiderent before Carl Greenidge fell leg before also for a duck.
Off-spinner Justin Bates began the slide in the previous over by removing Kevin Barrett for six as the hosts lost four wickets in five balls to plunge from 140-4 to 148-8.
Surrey were sent in on dampish wicket and former Warwickshire batsman Jason Ratcliffe stroked 49 as they reached 107-1 from 32 overs.
Sussex have two more group matches remaining this week against the MCC Young Professionals but cannot qualify for the semi-finals.
Sussex Cricket Board convincingly beat Dorset by 65 runs in their final match of the ECB 38 Counties competition at Weymouth.
Dorset, set a target of 254 in the 50 overs-a-side game, were never in the hunt and were dismissed for 188 with pace bowler Tim Van Noort taking 3-23.
James Chadburn earlier hit 69 while Chris Mole made 64 and Richard Jackson 43 not out as Sussex posted 253-8 after being sent in.
Sussex's second successive victory is not enough to put them into the quarter-finals as Berkshire, who beat them in the opening two games, go through.
Said Sussex Academy coach, Chris Waller: "I'm very encouraged by the way our young players have acquitted themselves in these matches.
"We lost twice to a very strong Berkshire side but one of the matches could have gone either way and all the team played well in our latest win."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article