Essex again suffered at the hands of Simon Katich and Glen Chapple as Lancashire won by 64 runs in the Yorkshire Bank 40 Group B match at Chelmsford.
Both players figured prominently in their side's County Championship victory on the same ground last week and they were at the forefront once again.
Put into bat, Lancashire reached 230 for 8 with Katich making 60 before they dismissed the hosts for 166 in 34.3 overs, with Essex losing their last four wickets in eight balls for three runs.
Katich underpinned the Lancashire innings with a steady run-a-ball innings that contained five boundaries, including a six off Saj Mahmood that cleared the ropes at deep extra cover.
Chapple, who had taken five for nine in Essex's humiliation when they were dismissed for 20 last week, took three for 33 including the vital scalp of Owais Shah who was beginning to pose a serious threat.
Hamish Rutherford and Shah had revived the Essex hopes with a partnership of 94 in 17 overs after the first two wickets had fallen cheaply.
Rutherford played fluently, timing the ball sweetly and hitting cleanly, and he completed a 52-ball half-century with six boundaries including two sixes, one off Jordan Clark and the other off Simon Kerrigan.
Shah was the more subdued although he was quick to pounce on any loose deliveries, also striking Kerrigan over the ropes.
But after they had given Essex relief, the loss of three wickets in five overs for 21 runs put Lancashire back in firm control.