Lancashire survived a late onslaught from Graham Napier to secure a 28-run win over Essex in the Clydesdale Bank 40.
Stephen Moore, Steven Croft and Paul Horton all hit half-centuries as Lancashire posted 258 for nine in their 40 overs in the Group A clash at Old Trafford.
Essex looked in trouble on 139-6 in the 28th over in reply before Napier smashed 51 in just 25 balls in a quick-fire 68-run partnership with Greg Smith to give them a fighting chance.
Once Napier holed out to a brilliant catch from Croft, Smith continued the fightback with 44 from 40 deliveries.
But, in the end, the Eagles fell short as they were bowled out for 230 with 15 balls left, Lightning spinner Gary Keedy claiming 3-49.
Moore and Croft gave Lancashire a lightning start after winning the toss.
They both brought up their half-centuries at faster than a run-a-ball, with Moore smashing a six off Tymal Mills to bring up their 100 partnership off 77 deliveries.
David Masters then struck twice in an over. First, Croft was trapped lbw for 53 and then Karl Brown chipped the ball to Mark Pettini for 15 as Lancashire slumped from 130 for one to 148-4. Horton, however, led the rebuilding with 54 from 53 balls.
Alviro Petersen and Pettini made a bright start for Essex until Ajmal Shahzad claimed his first wicket at Old Trafford as a Lancashire player by bowling Petersen for 24.
Pettini, who was dropped by Horton on nine, added just eight more.
After Tom Westley was involved in a mix up which saw Adam Wheater run out for a duck, he put on 56 with James Foster to keep Essex in the game before being caught on the boundary by Mahmood for 33.
Foster made 41 before being bowled by Keedy, and when Michael Comber was run out for a duck two overs later, the game looked over.
Napier and Smith ensured Lancashire were tested, with Mahmood suffering the brunt of the attack as his eight overs went for 60.