Three goals in the space of five second-half minutes saw Shamrock Rovers maintain their steady progress as Drogheda’s season continues on a downward spiral.
There was little to suggest for almost 70 minutes that there would be three goals between them in the end but once Rovers opened their account United folded.
In a first half that wasn’t short on perspiration but lacking inspiration in the final third, Drogheda just shaded it in terms of the few opportunities created.
The home side had what looked like a solid penalty shout turned down after eight minutes when Derek Foran bundled over Graham Rusk as he raced into the box.
Minutes later Rovers went close when James Chamber put his header narrowly wide.
A lively start to the second half brought a decent chance at either end as firstly Thomas Stewart raced onto a hopeful punt from defence but dallied as the home defence closed him out and then Gavin Brennan lifted his effort wide.
Gary McCabe was only on the park three minutes when he opened the scoring heading a Stephen Rice cross in at the back post. Within 60 seconds Sean O'Connor's wonderful strike from way out beat Gabriel Sava and the same player turned provider for McCabe to nod home on 74 minutes to wrap up the win.
DROGHEDA: Sava, Quigley, Prendergast, O'Conor (McGahon 78), Hynes, O'Neill, G Brennan (Marks 78), Grimes, Rusk (Brady 78), Gannon, Daly.
SHAMROCK ROVERS: Brush, McCormack (Sullivan 57), Powell, Foran, Oman, Chambers (Robinson 76), Rice, Finn, O'Connor, Dennehy (McCabe 66), Stewart.
Attendance: 1,010.
Referee: D Tomney (Dublin).
