Martin Russell scored twice to end any pretentions no-league Wayside Celtic had of causing an FAI Cup shock at Richmond Park.
Russell, who scored when restored to the team after a three-month absence in their last match at Finn Harps, retained his eye for goal with strikes in each half to see the Premier Division side safely through.
Any jitters the home side hay have had were eased by 23 minutes when they deservedly took the lead. Mark Weir's error from a Ger McCarthy cross presented teh ball to Russell who drilled it under goalkeeper Alan O'Sullivan.
Wayside might have been level within three minuted, but team-mate, Jimmy Hobson, got in the way of a goalbound shot from Alan Byrne. Hobson then turned Colm Foley only to shoot into the sidenetting a minute before the break.
Russell's unitentional second goal on 54 minutes killed off Wayside's challenge. Liam Kelly made the goal with a burst through the middle to lay the ball off to Russell whose miss-hit cross sailed over O'Sullivan and into the net.
Wayside midfielder Alan Byrne was then sent off following two yellow within three minutes.
Russell provided the corner for Foley to head home St Patrick's third goal on 73 minutes.
Alan McHugh got Wayside's consolation goal with a long-range chip on 86 minutes before substiture Michael Holt scored his first goal for the club and St Patrick's 4 of the night.