A change in formation in the 70th minute proved profitable for Derry City at the Brandywell, Stephen Kenny playing a trump card against a defensive St Patrick's Athletic.
Having opted to switch to a 4-3-3 formation, Derry finally got the breakthrough following a break on the left flank.
Steven Gray left his full-back berth to race to the by-line and his low centre found the advancing Gareth McGlynn who diverted the ball home at the back post for the game's only goal.
With Cork City defeated in Drogheda, Derry moved a point closer to the Leesiders as St Pat's poor run continued.
The visitors didn't get off to the best start when losing left-full Darragh Ryan after just 18 minutes with an ankle injury.
However, the same player did well to head the ball of his goal-line in the 13th minute following an in-swinging Kevin Deery corner.
Derry's towering centre-back Clive Delaney met the centre but Ryan was well positioned to head the ball clear.
The home side enjoyed success on each flank with right-sided midfielder McGlynn forcing Gary Rogers into a save in the 21st minute.
Pat's opted to play deep, regularly getting large numbers behind the ball but Derry threatened again at another corner when Rogers did well to push another Delaney header over his crossbar on 32 minutes.
Five minutes after the break Pat's injury worries were compounded when their leading hitman Mark Quigley was replaced, the striker appearing to pull-up with a possible hamstring problem.
As the game progressed, Pat's continued to drop deep with the home side frustrated at so many men behind the ball.
However, the visitors were presented with a superb chance to break the deadlock in the 69th minute following a mistake in the Derry defence.
Delaney played a loose square pass to Gray and the alert Ryan Guy nipped in but his shot was directed at Derry keeper Gerard Doherty and he had an easy save to make from 18 yards.
With 20 minutes remaining Kenny changed his system to a 4-3-3 formation in an attempt to penetrate the Saints' two banks of four.
And that switch proved effective within five minutes, the home side deservedly breaking the deadlock.
Gray made his first run down the left flank and while his low centre evaded two players, the advancing McGlynn pounced to divert the ball home at the back post.
Pat's attempted to push forward during the latter stages of the match, with Garret O'Connor flashing a shot over the crossbar with two minutes remaining.
Kenny, no doubt, will be delighted with the result given his current injury list and with a trip to Sligo Rovers on the horizon this Friday night, his hopes of taking nine points from three matches remains on course.