Carrickfergus, Waringstown, Lisburn and North Down are through to finals day of the Lagan Valley Steels Twenty20 Cup after a dramatic night of action.
Instonians, who had appeared to be in control of Group A, lost out on net run rate after losing by 46 runs at Carrick.
In the same group Waringstown were indebted to an unbeaten 77 from just 60 balls from James McCollum as they beat Derriaghy by 86 runs at The Lawn.
Derriaghy managed just 87 for five batting second.
In group B North Down secured top spot with a seven-wicket win over CIYMS at Belmont. John Matchett struck 93 for the holders who are out of the competition after losing all three of their group games.
Lisburn are the other qualifiers from group B after beating CSNI by just six runs at Stormont.
The semi-final draw sees Waringstown face North Down at The Lawn while Lisburn will have home advantage against Carrickfergus.