Defending champions Middlesex went down to their sixth consecutive Twenty20 Cup defeat as Mark Pettini led Essex to an eight-wicket victory at Chelmsford.
Eoin Morgan and Dawid Malan each made 31 as the visitors were bowled out for 148 in 19.2 overs, Pakistan spinner Danish Kaneria picking up 3-21.
Pettini then struck 80 not out as the hosts got home with six balls to spare.
Essex go above Hampshire to sit third in the South Division, while Middlesex remain rooted to the bottom.
After winning the toss, the visitors were reduced to 8-2 when Neil Dexter was run out and Shaun Udal was caught by Alastair Cook off the bowling of Graham Napier.
Tyron Henderson (28) and Billy Godleman (19) led a fightback of sorts before both they and Owais Shah fell in quick succession.
Morgan and Malan then shared 60 for the sixth wicket, but both were dismissed by Grant Flower, the last five Middlesex wickets falling for 28 runs.
Pettini then shared an opening stand of 61 with Cook (21) and an unbroken third-wicket partnership of 63 with Matt Walker as Essex eased to their fourth Twenty20 Cup win of the season.