Sussex will play local rivals Kent in the last four of the Twenty20 Cup while Lancashire have been paired with Gloucestershire in the other semi.
The matches will take place at Edgbaston 1130 BST and 1500 BST on 4 August but it has yet to be decided which semi will be played first.
The two winners will contest the final at 1915 BST on the same day.
"We've had some real tussles with Kent in the past," said Sussex captain Chris Adams. "We know each other very well."
Lancashire Lightning vs Gloucestershire Gladiators
Sussex Sharks vs Kent Spitfires