Hampshire begin the defence of their 40-over title on Friday when the Yorkshire Bank 40 bursts into life with the first of four games in as many days on Sky Sports.
The Royals bagged the crown in dramatic fashion last year, edging Warwickshire by virtue of losing fewer wickets after the scores finished level in the final at Lord's.
Essex are their opponents first up this season in what promises to be a demanding competition featuring the 18 first-class counties, plus Scotland, the Netherlands and the Unicorns.
Only the top team in each of the three randomly-selected groups are guaranteed to make it through to the semi-finals, where they will be joined by the best second-placed team. Then it's onwards to HQ for the final on September 21.
For full coverage details, click here. Before the tournament gets under way, Bumble, Bob Willis and Paul Allott shared their thoughts...
Paul on Group A
Teams: Kent, Netherlands, Northamptonshire, Nottinghamshire, Sussex, Warwickshire, Worcestershire
This is a pretty tough group but I'm picking Sussex and Warwickshire as my two to watch. Sussex reached the semi-finals last year and have recruited well. Chris Jordan (pictured below) had huge potential at Surrey and he's hit the ground running at Sussex where his early Championship form has been brilliant: he's got the potential to be a fine all-rounder in one-day cricket. Rory Hamilton-Brown is regarded as one of the best attacking batsmen in one-day country cricket and needs to re-establish himself after the trials and tribulations at Surrey. Then there are the old heads of Ed Joyce, Michael Yardy and Chris Nash, plus Monty Panesar is lurking in the wings. So it's a good blend and Joyce will bring some fresh energy to the side as captain.
Warwickshire, last year's beaten finalists, have got a phenomenal bowling line-up with the likes of Chris Wright, Keith Barker, Boyd Rankin, Chris Woakes and their overseas player Jeetan Patel. New coach Dougie Brown was a good all-rounder but his speciality was one-day cricket and his on-field experience will rub off on the team now that he's moved upstairs. Potentially, they've got one of the best all-rounders in England in a resurgent Rikki Clarke; he's got absolutely everything. He has the ability to bowl a quick ball and bats in an uninhabited way and his catching is second to none.
Elsewhere, I'll be interested to see if James Taylor can finally establish himself through his Notts performances. He looks to have been overtaken in England circles by the likes of Bairstow and Buttler, but I don't think he's out of the international frame so long as he can consolidate a bit. My other player to watch is a little left-field - David Willey from Northants. He averages around 30 with both bat and ball in first-class cricket, which is pretty good for a youngster. He scores runs down the order and takes the new ball; I'm looking for him to get an England Lions spot in the near future.
Bob on Group B
Teams: Derbyshire, Essex, Hampshire, Lancashire, Scotland, Surrey, Durham
As the current white-ball champions in both forms, it's hard to look past Hampshire - they have bags of experience in the one-day game and know how to win competitions. The ever-reliable Michael Carberry (pictured below) is one to watch in the batting department and Sean Ervine is a very capable all-round cricketer. I also like the look of Surrey. While they will struggle to win Championship matches at the Oval, they'll be pretty potent at the one-day game and will be better drilled than last season, particularly if Graeme Smith can get them off to a good start. Jade Dernbach is a very capable one-day bowler, who knows how to bowl at the Oval even if he's had a bit of a rough ride with England.
Derbyshire will be concentrating on staying in division one of the Championship, while I think Essex are a poor side in all forms of the game and Scotland will struggle to be anything but no-hopers. I always tend to under-estimate Durham and pick the opposition to win when we cover their home games only for Phil Mustard to smash a hundred or Chris Rushworth to bowl the opposition out but I don't think they should be as competitive as Hampshire or Surrey.
DID YOU KNOW? Hampshire have not beaten Essex away from home in a one-day match since winning by 85 runs at Southend-on-Sea in 2001 - courtesy of an unbeaten 105 by Zimbabwean Neil Johnson.
Bumble on Group C
Teams: Glamorgan, Gloucestershire, Leicestershire, Middlesex, Somerset, Unicorns, Yorkshire
I'm going left-field with my prediction. I'm picking two to progress to the semi-finals from the same group - Yorkshire and Gloucestershire. I think that Gloucester could well be the dark horses of the competition, so I'm going to have a punt. The bookies have them at 33-1 at least, so I'll put a little saver on them.
I really like Yorkshire - they are such a good team. Their coach, Jason Gillespie, has settled in very quickly and they've got a good, solid captain in Andrew Gale. They've also got some very exciting players. I like Azeem Rafiq - I think he's going to be excellent in one-day cricket - and Moin Ashraf. Then you've got Bairstow, Root, Lyth, Gary Ballance. Richard Pyrah (pictured above) has been around a bit but he is another lad to look out for. When you put Tim Bresnan into that line-up and Jack Brooks, who they've signed from Northants, plus a bit of Liam Plunkett, I think they are well equipped to do well!
DID YOU KNOW? Leicestershire's recent record against the West Countrymen is not so good - winning just one of the last nine encounters dating back to 2000.
Watch Essex take on Hampshire in the opening match of the Yorkshire Bank 40 this Friday from 4pm on Sky Sports 3 HD.