BOHEMIANS' boss Aaron Callaghan named four players in his starting line-up -- Owen Heary among them -- who had been ruled out in the build-up to the game. But the Boynesiders weren't the least bit distracted and after only two minutes Paul Crowley had a shot deflected wide for a corner kick.
Mulvenna eventually broke the deadlock on 24 minutes when he ghosted in between two defenders and rifled home a shot from the edge of the box, already the Drogs were in the driving seat in terms of that second place.
A second chance for the former Dundalk ace was wasted when Sean Brennan broke through on goal, but instead of shooting opted to lay off to Mulvenna who got the ball caught under his feet at the vital moment.
That miss was quickly forgotten, though, as Stephen Quigley made an incisive run down the left flank and laid off to Mulvenna who shot past keeper Greg Murray from close range.
Drogheda would have been worthy of that 2-0 lead going into the break, but just before referee Hancock's half-time whistle Drogs keeper Gabriel Sava spilled the ball, under pressure from Dinny Corcoran, into the path of Evan McMillan who fired to the bottom corner to put the result back in the melting pot.
The Boynesiders didn't push the panic button, though, and Ryan Brennan and John Sullivan both went close just after the interval before Alan McNally restored their two-goal lead on 49 minutes with a header from Philip Hand's corner - his second goal in as many games.
There was an anxious moment for Drogheda when Keith Ward struck a 25-yard free kick against the post, but there was no way back for Bohemians and after Mulvenna was denied by a Murray save the Boynesiders pressed home their advantage with a fourth goal on 69 minutes, Mulvenna pouncing on a mistake from the keeper to plunder his hat-trick goal from close range.
The match ended on a sour note for the man of the match when he was stretchered off following an innocuous-looking challenge in the 84th minute.
However, that didn't dampen the party mood too much as Cooke and his players made their way to the away supporters in the Des Kelly Stand and celebrated another famous result - Drogheda's first win at Dalymount for six years. PFAI members' bemusing decision not to pick any Drogheda players on their Team of the Year surely acted as a motivational tool on Friday night as the Boynesiders crushed Bohemians at Dalymount Park.
The small matter of cementing second place in the table at the expense of St Patrick's was another reason to chase all three points, and this looked like a tall order against a Bohs side who had their sights set on securing the final Setanta Sports Cup qualifying position.
Indeed, with Drogheda's three top goalscorers - namely Declan O'Brien, Peter Hynes and Gavin Brennan - all suspended, there were genuine concerns about where the goals were going to come from.
But manager Mick Cooke has been quick to praise the whole squad for their contribution this season, and in their hour of need one of those squad members - Tiarnan Mulvenna - rose to the occasion with a sensational hat-trick.
The Dundalk native has been kicking his heels on the subs bench for large chunks of the campaign, and perhaps there was an element of his own personal frustration as he came out and tore apart the usually water-