Hampshire Royals or Glamorgan will meet Nottinghamshire Outlaws or Somerset in the Yorkshire Bank 40 Final at Lord's on Saturday 21 September, after ECB revealed the schedule for the semi-finals of the competition.
Holders Hampshire host their Welsh opponents at the Ageas Bowl on Saturday 7 September before the final line-up is completed on the evening of Monday 9 September when Notts welcome 2010 and 2011 runners-up Somerset to Trent Bridge.
Notts have been strong throughout the competition, and have James Taylor and Samit Patel available for their match-up against a Somerset side which will feature Craig Kieswetter and Nick Compton.
Glamorgan, who qualified as the best runners-up from Somerset's group meanwhile will be the underdogs for their match against Hampshire, who will be missing Michael Carberry - who has been recalled by England for their ODIs against Australia and Ireland.
The final and finale of the domestic summer takes place at Lord's on Saturday 21 September.
In addition to what promises to be a fine match, Lord's is also hosting a family fun day on the Nursery Ground, featuring fairground stalls, face painting, balloon modelling a picnic area and a speed bowling challenge for budding cricketers.
Tickets are on sale now, priced from £25 for adults and at just £5 for under 16s.