Ben Duckett held his nerve to help Northamptonshire launch the defence of their Twenty20 title with a thrilling three-wicket win over Yorkshire at Headingley.
Steelbacks highlights were four wickets for 25 runs on debut from New Zealand seamer Ian Butler and a brutal 43 at the top of the order from David Willey - hero of last summer's Edgbaston final against Surrey - before Duckett outdid Yorkshire's hard-working collective in their North Division opener.
Liam Plunkett and Tim Bresnan's 54-run stand, from a very wobbly 87 for six, made a match of it by rescuing 162 for seven after the Vikings chose to bat.
It was ultimately insufficient but confirmed only off the penultimate ball of the match, when Graeme White struck the only delivery he faced past point for four off Ryan Sidebottom to get the visitors home - with Duckett unbeaten on a career-best 39.
Durham were also North Division winners, in Friday's opening round of matches, thanks to an unbeaten 80 from Scotland batsman Calum MacLeod on debut for his new county.
He hit seven fours and two sixes from 56 balls, veteran Paul Collingwood adding 62 in a fourth-wicket stand of 113, as Durham posted 173 for four despite a sticky start at home to Worcestershire.
Debutant opener Richard Oliver made 43 in the run chase, but the visitors were all out for 144 - Collingwood completing a fine all-round performance with three for 29.
Samit Patel hit 56 out of 182 for five in Nottinghamshire's 33-run win over Lancashire at Trent Bridge.
Steven Mullaney took three for 46 against his old club as the Lancastrians fell short, despite Jordan Clark's defiant 44 from only 20 balls.
Leicestershire began with a 27-run win at home to Derbyshire - despite veteran Australian batsman Marcus North's 90 from only 47 balls.
North hit six sixes and six fours but found precious little support, in pursuit of a Leicestershire total of 197 for four in which evergreen New Zealander Scott Styris (63no) top-scored.
Nathan Buck took three for 26 for Leicestershire.
In the South group, Somerset's Australian left-armer Dirk Nannes (four for 21) won the battle of the seamers with Gloucestershire's James Fuller (four for 32) as the visitors edged the west-country derby at Bristol.
Half-centuries from Craig Kieswetter (55) and Alviro Petersen (51) gave Somerset a working total of 156 for eight, and then Hamish Marshall (54) could not lift Gloucestershire above 138 all out.
Leg-spinner Max Waller also picked up three for 22 for Somerset.
Last year's beaten finalists Surrey suffered a last-ball defeat to Sussex at Hove.
Jason Roy (57) and Gary Wilson (50) hit half-centuries as Surrey amassed 171 for seven, while slow left-armer Ashar Zaidi took three for 32 for the hosts.
Luke Wright led the Sussex scorers with 56 - but their chances looked slim when Chris Jordan was eighth man out with just four balls remaining and 15 runs needed.
However, Ben Brown blasted Jade Dernbach for six and Yasir Arafat hit the final two balls for four to seal a two-wicket home success.
At Southampton, Glamorgan mustered 161 for seven against Hampshire - for whom left-arm spinner Danny Briggs took three for 26.
It proved enough as the hosts could only total 151 for six. Matt Coles (42) led the scoring, with Will Owen taking three for 32 in the Welsh county's 10-run triumph.