Essex are on course to reach the final of the Bob Willis Trophy after a thrilling three-wicket win over Delray Rawlins and his Sussex teammates at Hove left them with the only 100% record in the competition.
Simon Harmer set up victory by claiming his 20th five-wicket haul for the county champions as Sussex were bowled out for 141 in their second innings, leaving Essex with a target of 196 in 52 overs.
George Garton revived home hopes with four wickets, including Alastair Cook for the second time in the match, and when Mitch Claydon took two wickets in an over, they were seven down needing 24 to win. But Paul Walter and Aaron Beard held their nerve, Beard hitting the winning boundary with 6.1 overs to spare.
Earlier, Sussex struggled to make headway against Harmer's accuracy and a seam attack admirably led by Jamie Porter, whose three wickets gave him eight in the match.
The South African off-spinner Harmer completed his five-for by removing Meaker and the dangerous Rawlins, the only Sussex batsmen who looked comfortable against him. Rawlins made 40 off 42 balls and deposited Harmer for successive sixes over mid-wicket before missing a sweep shot.
Rawlins spent 73 minutes at the wicket, he would hit 6 fours and 2 sixes.