Keegan hits wondergoal to get Shels dreaming
Shelbourne, finalists in 2012 and semi-finalists a year later, can dream of another cup run following this victory secured by Jordan Keegan's 17th-minute strike at Tolka Park.
Shelbourne 1 Waterford United 0
After absorbing some early pressure, the First Divison leaders bossed the first half.
Dylan Connolly was denied by the legs of Kevin Burns in the Waterford goal on 10 minutes but he was helpless to prevent the opener seven minutes later.
Everton-bound defender Ryan Robinson began the four-man move that ended with Keegan dropping his shoulder inside the box and curling into the top corner from 10 yards.
Waterford may have undergone cutbacks in recent weeks but keeping hold of Ipswich Town loanee Jack Doherty has been their saving grace.
His trickery had Shels on alert and a dinked cross to Paul Quilty on 25 minutes would have yielded the equaliser had the striker applied a proper connection with his head.
Connolly continued to be a menace for the Blues in the second half as six minutes after the interval he cut in from the left and drew a save from point-blank range by Burns.
The Waterford stopper had to be at his best again three minutes later when Jake Donnelly's ferocious drive was tipped over for a corner.
The visitors remained well in the tie and wasted a glorious chance in stoppage-time to force a replay.
Doherty's free-kick eventually fell at the feet of Thomas Whitty only for the sub to blaze his shot over from eight yards.
Man-of-the-match Doherty might also have equalised at the death had his volley been a yard more accurate.
Shelbourne – Murray; Gannon, Robinson, Desmond, Hand (Dixon 77); Quinn, Donnelly; Murtagh, Keegan (Coughlan 70), Connolly; Murphy.
Waterford United – Burns: Whittle, Barrett, Delaney, O'Donovan; Doherty, O'Connor, Sullivan, Croke, Drohan (Whitty 76); Quilty (Corcoran 88).
Referee – R Harvey (Dublin)