Harris boost for Dragons
James Harris will make his first limited-overs appearance of the season when the Welsh Dragons take on Durham in Group B of the Clydesdale Bank 40.
The seamer returned from a groin injury to make his first start of the campaign in Glamorgan's LV= County Championship game against Leicestershire last week and will now look to hit the ground running in 40-over cricket.
Durham, currently winless and bottom of Division One in the championship, are full of confidence in one-day cricket having won three of their first four encounters.
Worcestershire are aiming to build upon yesterday's oustanding victory over Group A table toppers the Netherlands against Gloucestershire.
The Dutch were dismissed for just 57 en route to a nine-wicket defeat that left Worcestershire five points adrift of the leaders with three games in hand.
James Fuller is in line for a first List A appearance of the season for Gloucestershire after being chosen in a 12-man squad.
Middlesex will again have England international Eoin Morgan in their ranks as they tackle Lancashire.
The third-placed Red Rose, meanwhile, are seeking a victory that would crank up the pressure on the aforementioned top two.
In Group C, second-placed Sussex aim to leapfrog Warwickshire by overcoming Derbyshire, while Northamptonshire target their first victory of the campaign against Kent.