The SSE Airtricity League Premier Division title race was blown wide open at Richmond Park as Christy Fagan's second-minute goal gave champions St Patrick's Athletic a massive victory over league leaders Dundalk.
The league's top scorer took his tally to 17 for the season when he pounced on a Brian Gartland mistake after just two minutes to fire past Peter Cherrie and end Dundalk's unbeaten league run, which had stretched back to April 25.
The result keeps the Saints' slim hopes of retaining their title alive.
Liam Buckley's side are now eight points behind the Lilywhites with six games to play but more significantly, Cork City are just three points off the pace after their 1-0 win over Shamrock Rovers.
Both managers made changes to their respective sides. Pat's, who advanced to the FAI Cup quarter-finals with a 1-0 win over Shelbourne on Monday night, freshened up their starting XI with Ger O'Brien, Ian Bermingham and Christy Fagan all recalled.
For Dundalk, Ruaidhri Higgins and John Mountney came in for Darren Meenan and Kurtis Byrne. David McMillan, who sprung from the bench to hit two goals in the win over Bohs, again had to settle for a place on the bench.
A cracking first-half started in spectacular fashion. The crowd, who took part in a minute's applause in recognition of the late former Dundalk chairman, Des Denning, had just settled into their seats when Pat's drew first blood after just two minutes.
Keith Fahey set Conan Byrne away on the right and when Brian Gartland made a complete mess of trying to flick his cross away, Fagan pounced to slot the ball low past Cherrie.
Dundalk responded well to the setback and they should have drawn level seven minutes later. Some good hustling on the touchline ended with Daryl Horgan sending Hoban through into the penalty area. Towell overlapped to take control but his effort was well saved by Clarke from close range.
The visitors threatened again on the quarter hour. Again it was Hoban and Horgan who were heavily involved in the build up across the face of the Pat's 18-yard line. Horgan advanced to skip around Clarke but, despite the narrow angle, he managed to get his effort on target only for Bolger to clear off the line. Towell could only hook the loose ball over the top.
The game continued at a helter skelter pace and Ruaidhri Higgins and Daryl Horgan both found their way into referee Paul McLaughlin's notebook as the tackles flew in.
One man who somehow managed to stay out of trouble was Greg Bolger, the Wexford man was by far the best midfielder on display in the opening 45 minutes with his tigerish tackling and pressing causing plenty of disruption to Dundalk's flow.
The visitors were sweating again in the 22nd minute when Cherrie inexplicably let a harmless Forrester effort spill from his grasp. Thankfully for the Scottish goalkeeper, the ball spun just past the upright.
Towell got forward to support Hoban at all times and he thought he was in again in the 34th minute. Daryl Horgan blazed past O'Brien but his through ball was well cut out by Killian Brennan who made sure not to neglect his defensive duties.
Cherrie was employed again before the break, making two comfortable saves from Fagan and Byrne before racing from his penalty area to snuff out Bolger's attempt to get Forrester in behind the Dundalk back four.
A pulsating first-half ended with the natives up in arms after a Higgins foul on Keith Fahey brought just a free-kick, and not a second yellow card from referee McLaughlin.
The second-half opened with Pat's threatening again and Cherrie had to divert a Conan Byrne attempt around his post just seconds after the restart.
Stephen Kenny reacted by introducing McMillan and Donal McDermott in the 56th minute and the visitors pushed relentlessly to try and get back on level terms.
Patrick Hoban hooked a difficult effort over the top on the hour mark before a neat move on the right involving Sean Gannon, McMillan and McDermott ended with the Ashbourne man driving into the Rovers box but his cross was poor and was easily put behind for a corner.
Pat's had to pick their moments to break and the tireless Fagan was involved again on a rare excursion into the Dundalk final third in the 70th minute. It looked like he had lost possession on the edge of the box but Byrne steamed in to curl a pacey effort just over the top
Fagan received a standing ovation when he was withdrawn in the 73rd minute. His replacement, Mark Quigley, should have killed the game off seconds later when he was picked out by Forrester but, with nobody in a yellow shirt around him, he snatched at the chance and Cherrie gathered.
The closest the Lilywhites came to equalising came with 12 minutes to go. A Gannon throw in fell at the feet of McMillan. His cross curled devilishly towards the back post but Hoban just couldn't get the connection needed to take the ball past Clarke.
The fourth official had just flashed up four minutes of additional time when Dundalk again went within a whisker of claiming a vital point. McDermott's free-kick found Dane Massey in the crowded penalty area but his header went agonisingly over the top.