Lancashire survived a late onslaught from Graham Napier to secure a 28-run win over Essex in Group A of 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 for six 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.
England fast bowler Steven Finn took three wickets in seven balls as Middlesex beat Leicestershire by 31 runs at Grace Road.
Finn's burst sent the Foxes sliding to 49 for five as they chased a victory target of 242, and they were finally dismissed for 210 to give the Panthers their second win in three games.
Finn, left out of the England side for the first Test against the West Indies, finished with three for 30 in eight overs.
Hampshire thrashed Scotland by 89 runs in their Group B clash at Bothwell Castle, rolling their opponents for a modest 131.
Michael Carberry top-scored with 76 as Hampshire finished on 220 all out with two balls of their innings remaining, but the Saltires could not mount a credible challenge - Jean Symes' 33 their best score as all six Hampshire bowlers took wickets.
Kabir Ali, with two for 17 in six overs, and Danny Briggs - who returned two for 31 in eight - were the pick of the bowlers, while Majid Haq took three wickets for Scotland.
Half-centuries from Tom Maynard and Zafar Ansari helped Surrey maintain their winning start to the competition as they overcame Durham by 60 runs at the Kia Oval.
After winning the toss and electing to bat Surrey were in trouble on 47 for three - with Mitchell Claydon taking all three wickets in 12 balls - but Maynard's 77 steadied the ship and Ansari's unbeaten 60 helped the hosts to 221 for seven.
Durham lost wickets at regular intervals to undermine their chase and they were all out for 161, with Jade Dernbach, Stuart Meaker, Matthew Spriegel and Gareth Batty claiming two wickets apiece.
In Group C, Yorkshire's new Australian fast bowler Mitchell Starc made a great impression on his debut with three for 28 but it was Gary Ballance's 77 that propelled the home side to a seven-wicket win over Derbyshire at Headingley.
Ballance, in prime form at the moment, timed his innings to perfection as Yorkshire reached their 220-run target with 14 balls to spare.
The left-hander faced 60 deliveries and thumped six fours and four sixes, putting on 69 for the third wicket with Phil Jaques and an unbroken 70 for the fourth with Joe Root.
Glenn Querl starred with ball and bat as the Unicorns pulled off their first win of the season, beating Kent by four wickets with an over to spare at Canterbury.
The Zimbabwe-born all-rounder followed up best figures of four for 41 with an unbeaten 24 from 21 balls to see his side to victory.
Having played out a maiden from Matt Coles to leave the Unicorns needing 33 from four overs he went on to hit four boundaries in seven balls to make Kent pay for a self-destructive batting effort.
England all-rounder Luke Wright smashed a half-century as Sussex defeated Northamptonshire by 12 runs.
The Sharks were bowled out for 180 inside 36 overs with Lee Daggett taking four for 31 and Wright top-scoring by blasting 59 off 57 balls.
Despite David Sales' 51 off 70 deliveries, the Steelbacks fell short of their meagre target as they were limited to 168 for seven, Will Beer claiming two for 21.