Derry City raided Dublin for three points, putting themselves back in the title picture, as St Patrick's Athletic's season goes from poor to worrying.
Three successive losses means Pat's are in the bottom half and seemingly out of that title race but Derry showed that they are an improving collective.
A rare City attack was enough for the win, Northern Ireland international Liam Boyce finishing a sweet move decisively just shy of the half-hour mark.
City played with ample self-belief, epitomised by stopper Brian Maher who dealt with what little came his way. This, however, continued the bigger story of Pat's looking like a side that knows what it needs to do but does not know how to or who with.
Key high-name players are, if not out of sorts, playing below their capabilities.
Derry had to defend a lead for over an hour but rarely looked like surrendering it and it was hardly a siege in any event.
Pat's needed to show some early gusto here with diffidence never far away at the moment and Jay McClelland ran at the Derry defence two minutes in; his drive did not trouble Maher but at least it signalled Pat's purpose.
Then Seán Hoare, preferred to Tom Grivosti, worked Maher from a corner, with the returning Brandon Kavanagh enjoying the responsibility again and keen to dictate Saints' tempo.
And it was Kavanagh who had a chance at a 'worldie' but his volley from Simon Power's cross after ten minutes lacked the accuracy of which the diminutive Dubliner is capable.
Indeed, Derry barely left their own half in the first 20 minutes, but they had the body language of a team not concerned.
The visitors' starting side lacked pace, which could not be said of Saints, and the Candystripes could not afford to leave open spaces for a counter. But they were growing into the contest, as evinced by the opener on 29 minutes.
Michael Duffy, perhaps the player of the season so far, played Ronan Boyce into space and his stinging cross was met by the head of namesake Liam, whose downward header was testament to his experience and quality.
He was one of a scatter of big-name off-season signings an, while Derry's decision to train Saturdays has resulted in some changes in their squad, they look like they are getting there under Tiernan Lynch.
Saints, however, are having their poorest spell since Kenny took charge.
What would they do in the second half to arrest the tide? Better Pat's play nearly brought a leveller within a minute, with Power's cross meeting the sliding Mason Melia but his connection was badly lacking power, to Maher's relief.
Then Adam O'Reilly put in a perfect cross into the goalmouth and it seemed a miracle that no Derry player connected, with both defecses stretched in a cracking start to the second half.
City's side has ample physique and Saints faced no easy challenge in prising its confident defence open. The crowd, however, sensed something might happen and Pat's continued on the forward foot.
Melia roasted Mark Connolly on 57 minutes and, though the excellent Sam Todd, the last man, blocked his run, the ball spun towards Power who should have done better but saw Maher save with his feet.
Perhaps Connolly was feeling something: he walked off injured shortly afterwards, as Lynch made a triple substitution to freshen the picture.
Kavanagh fashioned a little space outside the box on 64 minutes but sliced his effort just wide; like in recent defeats to Shelbourne and Galway, it was not for a dearth of endeavour that the Saints were struggling, with Power taking on auxiliary wing-back O'Reilly but flashing his shot over.
Cometh the hour cometh Chris Forrester, who was introduced for the final quarter, but the home fans were growing in frustration, Derry in self-belief, and substitute Aidan Keena's drive did not trouble Maher with 11 minutes remaining.
Another player keen to make an impact, Jake Mulraney, had his shot blocked, with Saints' end product consistent with a side struggling for goals.
Forrester tried an ambitious sprayed ball for Mulraney, which sailed into the crowd by the Camac, summing up where Pat's are at just now. Derry are rising.
St Pat's: Joseph Anang; Carl Sjöberg (Aidan Keena 71), Seán Hoare, Joe Redmond, Jason McClelland; Barry Baggley (Chris Forrester 67), Jamie Lennon; Simon Power, Brandon Kavanagh (Jake Mulraney 77), Zach Elbouzedi; Mason Melia (Kian Leavy 77).
Derry City: Brian Maher; Mark Connolly (Shane Ferguson 60), Hayden Cann, Kevin Holt; Ronan Boyce (Adam O'Reilly 46), Sadou Diallo (Robbie Benson 73), Karl Winchester, Sam Todd; Gavin Whyte (Paul McMullan 61), Michael Duffy; Ronan Boyce (Danny Mullen 61).
Referee: Mark Houlihan.
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