Rana Naved-ul-Hasan claimed three wickets as Sussex romped to a nine-wicket win over Middlesex in Group A of the Clydesdale Bank 40.
The Pakistani paceman scooped 3-21 as Neil Dexter's Panthers were skittled for only 123 at Hove.
The Sharks needed just 22.4 overs to knock off the runs, England all-rounder Luke Wright finishing unbeaten on 71 off only 68 balls.
Middlesex, who lead the way at the top of LV= County Championship Division Two after three wins from four matches, produced a woeful batting display after winning the toss.
All-rounder Gareth Berg hit 52 to emerge as the only Middlesex player to score above 20 in a pitiful effort that lasted only 36.5 overs.
Sussex had no such problems in reply, despite losing opener Matt Prior lbw to England team-mate Steve Finn in the second over of the chase.
Ed Joyce and Wright carried on undeterred, the former compiling a patient unbeaten 47 as Wright provided the fireworks at the other end.