Cobh Ramblers 0 Waterford United 1
An Alan Kirby penalty squeezed Waterford into the last four in this all-First Division clash at a packed St. Colman's Park.
Kirby shot home from the spot on 49 minutes for the only goal of the match.
There was no way back for Cobh whose skipper Willie Byrne was sent off for the hand ball which led to the penalty.
Donal Golden had wasted a glorious chance for Ramblers just before the break when shooting wide with only Blues keeper Anthony Fennelly to beat.